Arch. Dis. Chiidh. 1969, 44, 162.
`
`Hyperammonaemia
`A Variant Type of Deficiency of Liver Ornithine Transcarbamylase
`B. LEVIN, R. H. DOBBS, E. ANN BURGESS, and T. PALMER
`From Queen Elizabeth Hospital for Children, London
`
`The specific syndrome arising from an absent
`or low hepatic ornithine transcarbamylase activity
`has been termed hyperammonaemia (Russell et al.,
`1962; Levin and Russell, 1967; Levin, 1968). In the
`al., 1969) 2
`previous communication (Levin et
`cases occurring in mother and child are described.
`In this article, we record an infant who during the
`course of an investigation for the cause of his
`vomiting had an unexplained episode of illness in
`which he became lethargic, drowsy, and finally
`comatose, with convulsions. He was found to have
`a high plasma and CSF ammonia, and the diagnosis
`of hyperammonaemia was confirmed by assay of the
`urea cycle enzymes of the liver.
`Studies of the properties of the liver ornithine
`transcarbamylase in this patient suggest that he
`represents a variant type of deficiency of this
`This may be correlated with the relative
`enzyme.
`mildness of his condition, and the rapidity and
`recovery. The effect
`of clinical
`completeness
`of citric acid, glutamic acid, alanine, and arginine
`on plasma ammonia levels was also studied.
`
`Case Report
`A male, born on August 8, 1966, was the first child
`of unrelated parents in whom there was no family
`history of fits, mental defect, or other metabolic diseases
`toxaemia
`side. The mother developed
`on either
`during pregnancy which was terminated by induction
`at 36 weeks. The infant was normal but slightly
`immature, weighing 2*4 kg. He was breast-fed at
`first, then bottle-fed, and was apparently well for 6
`months, growing steadily along the 3rd centile for weight
`(Fig. 1). At 6 months he was admitted to Southend
`General Hospital on account of bronchiolitis. No other
`abnormality was noted at this time, and the milestones
`were normal. He weighed 6-5 kg. and took his milk
`and weaning diet well.
`Very soon after discharge he began vomiting occa-
`with
`It was effortless and unassociated
`sionally.
`
`Received October 17, 1968.
`
`However, it became
`malaise, anorexia, or constipation.
`increasingly troublesome and he ceased to gain weight.
`He was treated with atropine methonitrate ('eumydrine'),
`with no improvement, and at 8j months was readmitted
`for investigation. He was then a thin, lively infant
`There were no abnormal physical
`weighing 7 kg.
`signs, and the blood chemistry, urine microscopy,
`Radiological examina-
`and chromatogram were normal.
`tion showed no abnormality of the oesophagus, stomach,
`or upper bowel. The vomiting continued in hospital,
`occurring mainly in the evening, and often contained
`much of the day's food.
`During the first week he was quite lively, but sub-
`sequently became drowsy and increasingly difficult
`to rouse in the morning.
`His temperature rose to
`39 4 'C., the pulse to 136 per minute, and the liver, on
`which no comment had been made when he was ex-
`amined earlier for possible pyloric stenosis, was now
`enlarged to 3 cm. below the costal margin.
`His condi-
`tion deteriorated rapidly. CSF obtained by lumbar
`puncture gave normal results by the usual tests.
`Immediately after the lumbar puncture he collapsed
`and became semicomatose, with twitching.
`It was
`thought possible that the procedure had led to coning
`and medullary pressure consequent upon an intra-
`cranial space-occupying lesion, and 2 months after his
`first admission, May 7, 1967, he was transferred to the
`London Hospital for neurological investigation. He
`arrived deeply comatose and convulsing, remaining in
`this condition for over 36 hours. The fontanelle was
`tense and bulging. A further lumbar puncture pro-
`duced a blood-stained fluid containing no excess of white
`cells and a normal protein content. The liver was now
`still further enlarged, to 6 cm. below the costal margin.
`Numerous biochemical investigations, including blood
`urea (22 mg./100 ml.), gave normal results. The EEG
`was grossly abnormal and reported as showing 'probably
`severe structural damage possibly due to severe electro-
`lyte disturbance'. The echogram showed no mid-line
`shift and an air ventriculogram no abnormality.
`He was at first fed by gavage with a milk mixture,
`but because of regurgitation and convulsions this was
`replaced by intravenous glucose 18 hours after admission.
`Shortly after starting this he rapidly improved and
`was out of coma within 24 hours.
`Paper chromato-
`graphy of a specimen of urine taken shortly after
`162
`
`1 of 8
`
`

`
`,v20 13pproyl)(
`
`te
`
`c_ 4
`10"
`
`P-POrteo
`H
`
`4,
`
`Z1
`
`er
`
`I
`
`|
`
`Z
`
`G -
`
`H
`
`vt
`
`9
`coma
`
`c on ti ncliti
`
`Hyperammonaemia
`163
`the next 4 weeks. The EEG 4 days after admission
`All subsequent
`showed only slight residual abnormality.
`EEG's have been normal, both between meals and after
`protein ingestion. He was discharged a month after
`admission weighing 7-8 kg. and on a diet containing
`13-14 g. protein per day. He gained weight rapidly
`at home and resumed normal mental development.
`Within a few weeks he had lost all evidence of hypotonia
`and at 1 year old was beginning to stand and walk.
`At 15 months he weighed 9 kg. and was between the
`3rd and 10th centile for height. He was then able to
`say a few words.
`Progress was so good that his protein
`18 * 5
`g.
`daily.
`However,
`intake was increased to
`within two months he had lost a little weight, possibly
`associated with an attack of bronchitis, and the plasma
`In consequence, though he showed
`ammonia level rose.
`no adverse symptoms, the intake of protein was reduced
`to about the previous level, at which he has since
`remained.
`At 21 months he remained in excellent
`health and he was walking, running, and talking in
`short sentences. When last seen, at 2 years of age,
`he was a normal boy and had grown from below the
`3rd centile for weight and the 10th centile for height
`at 1 year to the 25th centile for both at 2 years (Fig. 1),
`while the bone age, which had been 6 months retarded
`at 1 year, was approximately at the chronological age at
`2 years.
`
`~~~~~~~~~~~~~~~~centil
`
`1*
`
`25th
`
`5
`
`_
`
`0
`
`80 -
`
`3 -
`> cr 7
`|
`
`00
`
`85
`
`5
`
`3
`6
`Age (months )
`
`121518
`
`21
`
`24
`
`FIG. 1.-Progress chart.
`
`Note improving weight and
`
`height gain on a low protein diet.
`
`admission revealed an excess of glutamine and uracil,
`
`This was
`suggesting a possible high blood ammonia.
`confirmed when the plasma ammonia was found to be
`182 ztg. NH,-nitrogen/ 100 ml. more than 48 hours after
`the start of the infusion. A provisional diagnosis of
`
`hyperammonaemia, possibly due to a congenital meta-
`
`bolic disorder, was made, and on May 12, he was
`
`transferred to the Queen Elizabeth Hospital for Children
`
`for further investigation. On arrival he was alert and
`
`hungry and able to smile, but seemed dazed, was
`
`hypotonic, and exhibited some indefinite ataxic move-
`
`ments of the arms. No abnormal physical signs were
`
`detected apart from the liver enlargement which had
`
`diminished.
`
`Enzyme assays on a biopsy specimen of
`
`the liver confirmed the presence of an enzyme defect of
`the urea cycle.
`Histologically there was a mild increase
`of fibrous tissue in the portal tracts but no evidence of
`Cirrho1SiS.
`Fasting levels of plasma ammonia ranged between
`40 and 90NH3g.NHi-N/100 ml., i.e. up to twice the upper
`A
`limit of normal, and rose to 160-250
`g.NHa-N/100 ml.
`after ingestion of protein (see Table II). A low protein
`diet of SMA ('adapted' milk) in 5 equally spaced
`Later, egg yolk and
`feeds was thereafter instituted.
`rice were added.
`Within a few days of admission
`he seemed almost normal, except for persisting liver
`enlargement which gradually returned to normal during
`
`Results of Laboratory Investigations
`The methods used are described in the previous
`paper (Levin et al., 1969).
`
`Plasma sodium,
`Biochemical investigations.
`potassium,
`chloride, standard bicarbonate, and
`pH determined on a number of occasions were all
`within normal limits.
`Serum calcium, magnesium,
`albumin,
`globulin,
`protein,
`phosphorus,
`total
`non-protein nitrogen, cholesterol, and uric acid
`were also normal. The blood urea ranged from
`10 to 22 mg./100 ml. in random estimations, though
`occasionally levels up to 28 mg./100 ml. were
`reached 3 or 4 hours after a protein meal. The
`liver function tests were normal except for the serum
`GOT which was moderately raised during the
`acute episode and for a time thereafter. The
`alkaline phosphatase was also slightly raised.
`There was only a slight increase in the urinary
`Paper chromatography
`excretion of amino acids.
`Quantitative
`showed a prominent glutamine band.
`analysis confirmed the increased glutamine excretion.
`
`Ammonia levels in plasma and CSF. The
`plasma ammonia level estimated 4 days after the
`onset of coma was 182 tLg.NH3-N/100 ml. (normal
`,ug.NH3-N/100 ml.).
`Thereafter it was
`10-45
`determined on many random occasions, the levels
`ranging from 40-237 ,ug.NH3-N/100 ml., depending
`
`2 of 8
`
`

`
`164
`
`TABLE I
`Effect of Varying Protein Intakes on Plasma Ammonia;
`Levels at 3-hourly Intervals Throughout Day
`
`Protein Intake
`(g./kg.
`body weight)
`
`0 hr.
`
`Plasma Ammonia (tLg.NH3-N!1O0 ml.)
`2h.15h.1 r
`9 r
`12 hr. 1S hr. 18 hr.
`3 hr.
`6 hr.
`9 hr.
`
`Levin, Dobbs, Burgess, and Palmer
`Plasma ammonia levels
`Protein loading tests.
`were also determined after fasting and 1, 2, 3, and
`There was a marked
`4 hours after a protein feed.
`rise, maximal at 3 or 4 hours after the meal, greatly
`in excess of the slight rise occurring in normal
`This rise in
`infants under similar conditions.
`plasma ammonia was not abolished or diminished
`by giving citric acid (0 5 g. or 1-5 g.) just before
`the protein meal, nor was glutamic acid (2 g.) any
`more effective (Table II).
`
`1-8
`1-4
`1-2
`
`64
`48
`41
`
`65
`93
`68
`
`171
`121
`77
`
`46
`
`126
`142
`57
`
`111
`83
`88
`
`68
`
`Plasma ammonia nitrogen
`
`o----o Alanine b-2q.
`Alanine 62q +
`Arginine 12 bq
`
`-
`
`.
`
`350.
`
`300
`
`250-
`
`200-
`
`50-
`
`100-
`
`50
`
`0
`
`25
`
`20
`
`1 5
`
`10
`
`5
`
`0
`
`E8
`
`a,
`
`E8
`
`E
`
`0T
`
`ime after dose (hours)
`
`FIG. 2.-Effect of ingestion of (a) L-alanine (0 6 g./kg.),
`(b) L-alanine (0-6 g./kg.) and arginine (0-125 g./kg.)
`Note
`together on plasma ammonia and blood urea levels.
`that the addition of arginine to L-alanine does not reduce
`the rise of plasma ammonia.
`
`Effect of ingestion of alanine and arginine.
`In some cases of protein intolerance associated
`with raised ammonia levels the latter are lowered
`by administration of arginine.
`Plasma ammonia
`and blood urea levels were therefore determined
`at hourly intervals for 4 hours after oral ingestion
`of L-alanine (0* 6 g./kg.), and after L-arginine
`(0 * 125 g./kg.) given with alanine (0 * 6 g./kg.) The
`After alanine, the
`results are shown in Fig. 2.
`plasma ammonia rose to the high level of 338
`tig.NH3-nitrogen/100 ml. after 3 hours, with a
`relatively small increase in the blood urea. L-alanine
`and arginine together induced an identical rise in
`plasma ammonia, but the increase in blood urea was
`
`presumably on the relation to the previous meal.
`The CSF ammonia level, measured only once, was
`32 [±g.NH3N/100 ml. (normal up to 10 ,ug.NH3-N/
`This was 11 hours after a protein meal,
`100 ml.).
`when the plasma levels 30 minutes before and 30
`minutes afterwards were 108 and 132 [.g.NH3-
`N/100 ml., respectively.
`
`Dietary protein and plasma ammonia. The
`effect of different levels of protein intake was assessed
`by determining the plasma ammonia at 3-hourly
`intervals over a period of 15 hours during the day
`at different levels of protein intake. The results
`(Table I) show that in general the less the protein
`intake, the lower the ammonia levels.
`In two
`at two different age periods,
`in which
`series,
`though the total protein was unaltered, the intake
`calculated per kg. body weight was less as he grew
`older, plasma ammonia levels were lower with the
`that
`This suggests
`lower intake
`the
`per kg.
`apparent increase in protein tolerance with age
`may be related to a decreasing protein intake per
`kg. body weight.
`
`TABLE II
`Plasma Ammonia Levels After Protein Ingestion;
`Effect of Citric and Glutamic Acids
`
`Protein Ionad
`vL LCI
`svs
`-as
`
`v
`
`lOg.
`
`lOg.
`
`ritri arid
`Q a X n s
`g. tu v3g. citric a-lu . .
`
`10 g.
`
`..
`
`10 g. + 1 5 g. citric acid
`
`IOg.+20 g.
`I
`t
`glutamic acid
`Urea mg./100 ml.J
`10 g. alone
`Urea mg./100 ml.
`
`,g.NH3-N/100 ml.
`HorIfe PoenLa
`Hours after Protein Load
`2
`3
`4
`1
`
`i 108
`
`132
`
`163
`
`152
`
`104
`
`138
`
`237
`
`123
`
`86
`
`170
`(16)
`
`14Ci
`
`155
`
`94
`
`240
`(17)
`143
`(15)
`
`251
`
`189
`
`200
`
`246
`(20)
`128
`(17)
`
`223
`
`148
`
`167
`
`137
`(21)
`116
`(18)
`
`Fasting
`
`45
`
`75
`
`7
`o,
`
`88
`
`71
`
`76
`(12)
`112
`(14)
`
`3 of 8
`
`

`
`Hyperammonaemia
`TABLE III
`Plasma Amino Acid Levels, Fasting and After Oral Ingestion of Protein or Amino Acids
`
`165
`
`Amino Acid
`
`(mg./
`
`Fsig 3 hr. After
`Protein Load
`/0ml)(mg./100 Ml.)
`
`3 hr. After
`Fsig
`(mg /100 ml) Alanine (6 2g.)
`(mg./100 Ml.
`
`Fatn
`(mg /100 m)
`m.loM.)
`
`..
`Glutamine ..
`Glutamicacid
`..
`Citrulline
`..
`..
`Ornithine
`..
`..
`Arginine
`..
`..
`Glycine
`.
`..
`..
`..
`Alanine
`Leucine
`..
`..
`..
`..
`Urea
`Ammonia (,ug. NH3-
`N/100 ml.)
`..
`
`200
`10
`010
`058
`0-84
`1-7
`3-4
`13
`14
`
`112
`
`23 0
`0 8
`010
`071
`0 75
`1-5
`4-4
`2 2
`17
`
`128
`
`172
`0-61
`008
`0*36
`0 29
`19
`2-0
`089
`12
`
`77
`
`18-5
`1-7
`Nil
`0*38
`0351
`13
`5 1
`048
`16
`
`338
`
`15-3
`1.0
`010
`0*45
`0-65
`2-7
`4-2
`079
`13
`
`40
`
`2 hr. After
`Alanine(62g.)g
`Arginine
`(1 -26 g.)l
`(mg./100 ml.)
`22-1
`2-5
`0 16
`1*5
`2 3
`2-6
`18-5
`055
`20
`
`15 Normal
`Adults
`(Fasting)
`(mg./100 Ml.)
`Mean ± SD
`10 8±0 8
`0 51+0-22
`045 ±017
`0*67±0*09
`1-5 ±0-42
`1-7 ±0-27
`2-8 ±0-63
`1*5 ±022
`14-50 (range)
`
`241
`
`10-45 (range)
`
`of these
`
`results
`
`is
`
`greater. The significance
`discussed below.
`These were
`levels.
`Plasma amino acid
`also determined on a number of occasions, and
`some of the results are shown in Table III. As in
`of hyperammonaemia, fasting
`other
`the
`cases
`glutamine levels were very high, and glutamic
`Both arginine and citrulline
`acid was also raised.
`levels were low compared with the normal, whereas
`After ingestion
`ornithine was within normal limits.
`of protein, there was a marked rise in glutamine but
`Alanine
`little change in the other amino acids.
`ingestion resulted in a rise in plasma glutamine
`and glutamic acid, with little change in the other
`It also caused a
`intermediates of the urea cycle.
`marked rise in plasma alanine. The effect of
`alanine and arginine given together was similar
`to that of alanine alone. The rise in glutamine
`and, more marked, in glutamic acid, was consistent
`with the failure of arginine to reduce the rise in
`plasma ammonia resulting from the alanine. As
`expected, there was a rise in plasma alanine and
`arginine.
`
`Amino acids in CSF. These were estimated
`on one occasion only, and the relevant levels are
`given in Table IV, together with those from normal
`Both glutamine and glutamic acid levels
`children.
`were higher than in the normal, whereas arginine
`was lower.
`
`These were determined
`Urinary amino acids.
`quantitatively on a specimen of urine obtained
`during his initial episode while he was still having
`glucose electrolyte infusion, as well as on urine
`obtained just before a protein loading test and 4
`hours after the ingestion. The results are shown
`
`in Table V, together with those from normal urine
`for comparison. The increased glutamine and
`glutamic acid excretion confirmed the qualitative
`In the first
`results of paper chromatography.
`specimen examined, the excretion of ethanolamine
`was very high. No explanation can be given for
`this; in the other two urines, the level of ethanola-
`Despite the low plasma
`mine appeared normal.
`arginine, the urinary concentration was normal in
`amount.
`
`TABLE IV
`Levels of Some Amino Acids in Cerebrospinal Fluid
`
`Amino Acid
`
`|patient
`17 Controls
`(mg.PatiMe). 8 mth.-I 1 yr. (mg./100 ml).
`Mean± SD
`
`(mg./10ml).
`
`..
`Glutamine
`Glutamic acid..
`..
`Citrulline
`Ornithine
`..
`..
`Arginine
`
`..
`..
`..
`..
`..
`
`8*3±1*2
`14
`002 (<004)
`015
`0-015 (<0 035)
`0-02
`0-07±0 05
`010
`008 0i34 +0*10
`
`TABLE V
`Levels of Some Amino Acids in Urine
`
`Amino Acid
`
`During
`Episode
`of Illness
`(mg.!g. N)
`
`After
`Fasting
`Protein
`(mg./g. N Ingestion
`(mg./g. N)
`
`Glutamine
`Glutamic acid
`Ornithine
`Arginine ..
`Ethanolamine
`Glycine ..
`..
`Alanine
`Histidine
`Lysine
`
`..
`
`..
`110-0
`085
`..
`.0. 53
`..
`23
`270
`..
`22 0
`..
`..
`97
`..
`44-0
`..
`2-4
`
`67
`1 7
`03
`058
`3 5
`500
`6-9
`560
`2-7
`
`38
`5 *7
`062
`082
`36
`640*
`9 5
`34 0
`3-4
`
`Normal
`Children
`(mg./g. N)
`
`16, 12
`05, 0*2
`015,0*17
`022,0 *72
`1*4,1*3
`8*0,5 *7
`5-0, 2-2
`80, 12*0
`0 75, 2-1
`
`4 of 8
`
`

`
`166
`
`Levin, Dobbs, Burgess, and Palmer
`
`TABLE VI
`Levels of Enzymes of the Urea Cycle in Liver
`
`TABLE VII
`Properties of Ornithine Transcarbamylase
`
`Patient
`(units)
`
`Normal (mean and
`range) (units)
`
`250
`
`Carbamyl phosphate
`..
`synthetase
`Ornithine transcarbamylase
`1288
`at pH 7 *0
`4332
`at pH 80
`13-5
`ASA synthetase
`115
`ASA cleavage enzyme
`Arginase .. 24,833
`
`320 (182-615)
`
`5183 (3950-6650)
`5787 (3900-9090)
`37
`177
`38,420 (24,600-56,300)
`
`1 unit = 1 ,tmole product formed/hr. per g. wet weight of tissue.
`ASA = argininosuccinic acid.
`
`These were
`Urea cycle enzymes in liver.
`assayed in a biopsy specimen of the liver obtained
`at open operation, and the results are shown in
`Initially, ornithine transcarbamylase
`Table VI.
`activity was measured by the method of Kulhanek
`and Vojtiskova (1964), using a glycyl glycine buffer
`at pH 8 * 0, and the result was just within the normal
`However, when it was determined by the
`range.
`method of Brown and Cohen (1959), using a tris
`buffer, pH 7 0, as in some of the earlier cases of
`hyperammonaemia, the activity was only 25% of
`the mean normal value, and the ratio of enzyme
`activities at pH 8 0O and 7 * 0 was double the normal
`value. As the reduction in activity was smaller
`than in other instances of hyperammonaemia (Levin,
`1968; Levin et al., 1969), the Km values of the
`enzyme for its two substrates, ornithine and car-
`bamyl phosphate, were determined (Table VII).
`The Km value for carbamyl phosphate was low,
`indicating a marked increase in the affinity for this
`substrate compared with the normal enzyme. The
`significance of these results is discussed later.
`The activities of other enzymes of the cycle were
`within normal limits, except for that of arginino-
`succinic acid synthetase which was reduced to
`about 33% of a normal control.
`
`Effect of enzyme block on pyrimidine
`instances
`other
`synthesis. As in
`of hyper-
`ammonaemia, there is an increased alternative
`utilization of ammonia to form orotic acid, uridine,
`and uracil, intermediates in the pathway of pyrimi-
`synthesis and breakdown (Levin,
`1968;
`dine
`Levin et al., 1969). The amount of these sub-
`stances excreted daily varied according to the
`Initially, when he was on a very
`protein intake.
`low protein diet, 18 mg. orotic acid and 18 mg.
`uracil were excreted daily, the latter being the
`earliest indicator of the defect in the urea cycle;
`even greater amounts were found when the protein
`
`Patient
`
`Normal Controls
`
`Km for ornithine.
`Km for carbamyl
`phosphate
`
`..
`
`0*89 mM
`
`034mM
`
`Activity at pH 7 0 (tris
`.1288 units"
`buffer)
`at pH 8 0 (glycyl glycine
`buffer)
`..
`Ratio of the 2 activities
`
`4332 units*
`33
`
`. .
`
`1 26 mM (mean)
`
`1*45; 0 *95 mM
`(mean)
`
`5183 (mean)
`
`5787 (mean)
`1 * 44 (mean)
`
`* 1 unit = 1 .tmole product formed/hr. per g. wet weight of tissue.
`
`Uridine, which
`slightly.
`intake was increased
`was absent from the urine when protein intake
`was very low, was also excreted in relatively high
`amount.
`
`Discussion
`The clinical course of this patient differed from
`that of other cases of hyperammonaemia presenting
`in infancy, in the relative mildness of the condition.
`Vomiting for no ascertainable cause together with
`failure to thrive from the age of 6 months were
`the only features until an acute episode of illness
`characterized by lethargy, drowsiness, and coma
`and again with no obvious cause. The similarity
`to the episodic stupor occurring in hyperammon-
`aemia suggested the possible diagnosis, afterwards
`in
`presenting
`In two other
`confirmed.
`cases
`infancy (Russell et al., 1962; Levin, 1968), severe
`brain damage was already apparent by the time
`In the present instance, there
`they presented.
`has been no evidence of this, and recovery on a
`low protein diet has, so far as can be judged, been
`complete.
`
`Protein requirements. The treatment of this
`elsewhere
`discussed
`has been fully
`condition
`(Levin, 1967; Levin and Russell, 1967).
`Unlike
`the other cases of hyperammonaemia, neither citric
`acid nor glutamic acid appeared able to reduce
`The
`in plasma ammonia.
`post-prandial
`rise
`only effective method of treatment in this case
`was found to be a strictly controlled reduction of
`protein intake.
`Studies over half a century on man's protein
`requirements have been largely concerned to
`establish optimal rather than minimal needs for
`daily
`intake of
`For adults
`individual.
`the
`a
`1 g./kg., for growing children 2-3 g./kg., and for
`infants 3-4 g./kg. body weight have been widely
`accepted as optimal, allowing an adequate margin
`for individual variation and the varying biological
`
`5 of 8
`
`

`
`Hyperammonaemia
`167
`and finally coma, usually occurring after the inges-
`It has long been
`value of the available protein.
`spontaneously.
`sometimes
`but
`of
`meat,
`tion
`appreciated, however, that an adult protein intake
`McDermott and Adams (1954) made a similar
`as low as 0 5 g./kg. is compatible with good health
`fistula in a man of 69 years with carcinoma of the
`physical
`performance
`(Hegsted,
`and adequate
`head of the pancreas in whom the liver was normal
`1968; Best and Taylor, 1961), and experimentally,
`and portal hypertension or collateral circulation
`nitrogen balance can be maintained on 18 g.
`After his operation the patient suffered
`was absent.
`protein daily, approximately 0 25 g./kg., using
`periodic episodes of confusion, with ataxia, stupor,
`protein of 100% biological value (Hegsted, 1968).
`and coma lasting 2 or 3 days, the only therapy
`For infants under 1 year, the minimal requirement
`of water,
`administration
`parenteral
`being the
`is not known, but, provided the biological value
`in adequate amounts.
`glucose, and electrolytes
`of the protein is high and absorption is not impaired,
`These episodes could be induced by giving a high
`it is probably very much less than the 3-5 g./kg.
`protein diet, urea by mouth, or such substances
`optimal.
`day accepted
`For example,
`as
`per
`as ammonium chloride or 'Resodec', an exchange
`breast-fed infants will receive little more than
`Even during periods
`resin containing ammonia.
`2 g./kg. body weight in the first few weeks of life,
`when the patient was symptomless, mentally clear,
`and less as they grow.
`and with a normal EEG tracing, blood ammonia
`In our patient the daily protein intake, almost
`levels were 50-75 [ug.NH3-N/100 ml., higher than
`exclusively as milk and eggs, was kept below 1 - 5 g./
`normal. When the symptoms were induced the
`kg. for over a year, except for a 7-week period,
`plasma ammonia rose sharply, and at the height of
`and this appeared to be sufficient to maintain good
`the symptoms reached a level of 300-600 tig.NH3-
`health, and physical and mental development.
`N/100 ml., and the EEG became grossly abnormal.
`Weight, linear growth, and bone age all accelerated
`After such very high levels a normal mental state
`during the second year of life (Fig. 1).
`Plasma
`Finally, when
`was not regained for several days.
`proteins and amino acids were normal.
`he was given a diet in which the daily protein was
`limited to 40 g., the patient remained well for
`several months with only occasional episodes of
`mild confusion, and his blood ammonia levels
`during asymptomatic periods were around 150
`[Lg.NH3-N/100 ml.
`similarity between these
`There is a striking
`findings in a 69-year-old man with an Eck fistula,
`and our own and other cases with a disturbance
`of the urea cycle (Levin, 1968; Levin et al., 1969).
`The evidence suggests that at least in the adult,
`and probably in children beyond the age of infancy,
`plasma ammonia levels of about 100 tig.NH3-N/100
`ml. and for short periods possibly up to 150-200
`,Lg.NH3-N/100 ml.,
`are compatible with good
`health and may give rise to no symptoms or changes
`in the EEG. The experience gained from this
`case confirms that this may also be true in infants
`at least after the first six months of life.
`
`failure
`Toxicity of ammonia. In hepatic
`the plasma ammonia level is commonly raised
`much above the normal range, and the levels above
`250-300 ,ug./100 ml. are usually associated with
`neurological manifestations, such as
`confusion,
`tremors, and muscular twitchings, while in hepatic
`coma levels of 500-600 ,ug./100 ml. or over may be
`(Sherlock,
`1958).
`Correlation
`between
`found
`plasma ammonia levels and signs and symptoms,
`however, is not close.
`Little is known about the levels at which blood
`ammonia becomes toxic when hepatic failure is
`However, observation from three separate
`absent.
`sources suggests that concentrations considerably
`above the accepted normal range may be well
`tolerated at least by the adult.
`In studying the
`utilization of ammonia as a source of nitrogen in
`protein synthesis, Furst, Josephson, and Vinnars
`administered ammonium acetate
`intra-
`(1968)
`venously to volunteers, giving as much as 200
`mEq within about 4 hours without observing any
`symptoms. The blood ammonia concentrations
`rose from an initial range of 50-80 jig. to 150-300
`lig.NH3-nitrogen/100 ml.
`Only when these limits
`were exceeded did the subjects begin to feel
`nauseated and dizzy, and some of them vomited.
`In the dog the diversion of blood from the portal
`vein into the vena cava by an Eck fistula is known
`to be associated with the so-called 'meat intoxica-
`tion', a neurological disorder of ataxia, convulsions,
`
`and
`blood
`raised
`intolerance
`Protein
`ammonia. A condition of familial protein in-
`tolerance associated with a raised blood ammonia
`has recently been described by Perheentupa and
`(Perheentupa and Visakorpi,
`co-workers
`1965;
`Kekomaki et al., 1967). They suggested that it
`was caused by an inherited defect of transport of
`basic amino acids, which resulted in a deficient
`excretion of arginine
`absorption and excessive
`and ornithine. As a result, the conversion of
`ammonia to urea was defective.
`In their cases,
`
`6 of 8
`
`

`
`168
`Levin, Dobbs, Burgess, and Palmer
`administration of arginine reduced blood
`oral
`age. He was found to have high levels of plasma
`ammonia levels, induced better growth, and in-
`ammonia, high urinary glutamine, and a character-
`creased the protein tolerance.
`In our case, how-
`istic pattern of plasma amino acid levels. The
`ever, the high plasma ammonia was not affected
`liver
`ornithine
`transcarbamylase
`activity
`was
`by oral arginine, and the excretion of arginine and
`decreased to 25% of the normal, compared with
`omithine was normal.
`5-7% in other cases.
`Investigations
`of other
`properties of the enzyme showed differences from
`the normal.
`Severe limitations of protein intake resulted in
`resumption of growth, and the child is now normal
`with no mental retardation.
`Plasma ammonia
`levels fell with restriction of protein, but are still
`above the normal. The requirements for protein
`and the relation of symptoms to plasma ammonia
`levels are discussed.
`It is postulated that, because of the unusual
`properties of the enzyme as well as the relative
`mildness of his condition, this child represents
`a variant type of liver ornithine transcarbamylase
`deficiency, due to a different mutation of the gene
`involved from that found in other cases.
`
`The help of the nursing staff, especially Sister R. W.
`Lucas, is gratefully acknowledged.
`Thanks are due
`to Mr. V. G. Oberholzer for his unstinting help with
`the analysis of the urine, and to Dr. N. E. France
`for the histological examination of the liver.
`
`REFERENCES
`Auerbach, V., diGeorge, A. M., and Carpenter, G. G. (1967).
`Phenylalaninemia.
`In Amino Acid Metabolism and Genetic
`Ed. by William L. Nyhan.
`Variation, p. 11.
`McGraw-Hill,
`New York.
`The Physiological Basis
`Best, C. H., and Taylor, N. B. (1961).
`Bailliere, London.
`of Medical Practice, 7th ed., p. 541.
`Brown, G. W., Jr., and Cohen, P. P. (1959).
`Comparative bio-
`chemistry of urea synthesis.
`I. Methods for the quantitative
`J. biol. Chem., 234, 1769.
`assay of urea cycle enzymes in liver.
`Furst, P., Josephson, B., and Vinnars, E. (1968).
`Utilization of
`ammonia nitrogen in healthy subjects and uraemic patients.
`In Nutrition in Renal Disease, p. 99.
`Ed. by G. M. Berlyne.
`E. and S. Livingstone, Edinburgh and London.
`Normal protein requirements in man.
`Hegsted, D. M. (1968).
`ibid., p. 1.
`Kekomaki, M., Visakorpi, J. K., Perheentupa, J., and Saxen, L.
`Familial protein intolerance with deficient transport
`(1967).
`of basic amino acids. An analysis of ten patients.
`Acta
`paediat. scand., 56, 617.
`Kulhanek, V., and Vojtiikovh, V. (1964). On the determination
`of ornithine-carbamyl-transferase activity.
`Clin. chim. Acta,
`9, 95.
`Genetic variation in metabolic disorders.
`LaDu, B. N. (1967).
`In Amino Acid Metabolism and Genetic Variation, p. 121.
`McGraw-Hill, New York.
`Ed. by William L. Nyhan.
`Amer. J. Dis. Child.,
`Arginosuccinic aciduria.
`Levin, B. (1967).
`113, 162.
`Hyperammonaemia: an inherited disorder of urea
`-- (1968).
`biosynthesis due to liver ornithine transcarbamylase deficiency.
`Symposium of the Society for the Study of Inborn Errors of
`Metabolism, Zurich, 1968.
`-, Abraham, J. M., Oberholzer, V. G., and Burgess, E. Ann
`(1969). Hyperammonaemia: A deficiency of liver ornithine
`Occurrence in mother and child.
`Arch.
`transcarbamylase.
`Dis. Childh., 44, 152.
`Treatment of hyperammonemia.
`-, and Russell, A. (1967).
`Amer. J. Dis. Child., 113, 142.
`
`It is now becoming
`Nature of enzyme defect.
`apparent that more than one genetic variation of
`an enzyme can occur, giving rise to syndromes
`which, though similar, are not identical (LaDu,
`1967).
`Such variation has been demonstrated
`in G6PD deficiency (Marks, 1964), heterogeneity
`of the aberrant enzyme being proved by differences
`in enzyme activity, substrate affinities, pH optima,
`stability, and electrophoretic
`mobility.
`It has
`also been postulated to occur in hyperphenylalanin-
`aemia (Auerbach, diGeorge, and Carpenter, 1967),
`histidinaemia (Auerbach et al., 1967), and fructos-
`aemia (Levin et al., 1968), and in other conditions.
`In our patient also the liver ornithine trans-
`carbamylase appears different from the normal
`one and from that found in the other cases of
`hyperammonaemia.
`There is a smaller reduction
`in its activity (Levin, 1968; Levin et al., 1969),
`and this only became apparent when the activity
`was measured using tris buffer at pH 7 0, being
`just within normal limits when measured at pH 8 *0
`In addition, the substrate affinities
`(Table VII).
`were quite different compared with those obtained
`These results suggest that the
`in normal liver.
`liver ornithine transcarbamylase in this patient
`is a variant form differing from that in the other
`cases of hyperammonaemia.
`
`Plasma ammonia, glutamine, and
`Genetics.
`glutamic acid levels were normal in the mother,
`both in the fasting state and after protein ingestion.
`No investigations were performed in the father,
`but there was no history of protein intolerance.
`It is therefore likely that the condition in this
`child is inherited as a recessive.
`In the other
`cases of hyperammonaemia, a dominant mode of
`expression has been suggested (Levin, 1968).
`This
`difference in the mode of inheritance would be
`explicable if the present case were, as postulated,
`a variant type due to a different mutation of the
`gene involved.
`
`Summary
`A new instance ofhyperammonaemia is described.
`He is an infant who began vomiting and failed
`to thrive from the age of 6 months, and who had
`an unexplained acute episode of illness with
`lethargy, drowsiness, and coma at 81 months of
`
`7 of 8
`
`

`
`Hyperammonaemia
`169
`with deficient transport of basic amino acids: Another inborn
`-, Snodgrass, G. J. A. I., Oberholzer, V. G., Burgess, E. Ann,
`Fructosaemia: Observations on
`error of metabolism.
`and Dobbs, R. H. (1968).
`Lancet, 2, 813.
`Russell, A., Levin, B., Oberholzer, V. G., and Sinclair, L. (1962).
`Amer. Y. Med., 45, 826.
`seven cases.
`Episodic
`Hyperammonaemia: A new instance of an inborn enzymatic
`McDermott, W. V., Jr., and Adams, R. D. (1954).
`stupor associated with an Eck fistula in the human with parti-
`defect of the biosynthesis of urea.
`Lancet, 2, 699.
`cular reference to the metabolism of ammonia. J. clin. Invest.,
`Pathogenesis and management of hepatic
`Sherlock, S. (1958).
`Amer. J. Med., 24, 805.
`coma.
`33,1.
`Glucose-6-phosphate
`dehydrogenase:
`(1964).
`A.
`Marks,
`P.
`In The Red
`Its properties and role in mature erythrocytes.
`Ed. by C. Bishop and D. M. Surgenor.
`Blood Cell, p. 225.
`Academic Press, New York and London.
`Perheentupa, J., and Visakorpi, J. K. (1965).
`
`Correspondence to Dr. B. Levin, Queen Elizabeth
`Hospital for Children, Hackney Road, London E.2.
`
`Protein intolerance
`
`8 of 8