30 J ulie 1977 SA MEDIE E TYDSKRIF 219

Porphyrin Precursors in Blood,Fluid in Acute

Urine and CerebrospinalPorphyria

V. A. PERCY,

SUMMARYFour patients suffering from variegate porphyria were in­vestigated during acute attacks. Porphyrin and porphyrinprecursor concentrations were determined in the urine,serum, cerebrospina! fluid (CSF) and stools. Levels ofde!ta-aminolaevulinic acid (ALA) and porphobilinogen werefound to be very much lower in CSF than in serum sam­pled concurrently, and were well below levels at whichthese substances have been shown to exert effects on

neural tissue in vitro. These findings cast doubt on thepossibility that ALA or porphobilinogen is responsible forthe production of the neural manifestations of acute por­

phyria.

S. Air. med. J., 52, 219 (1977).

The hereditary hepatic porphyrias have both clinical andbiochemical features in common. Patients with these dis­orders are subject to acute attacks which are generallyrecognized as being largely neurological or neuropsychia­tric in nature. During these attacks excessive amounts ofthe porphyrin precursors, delta-aminolaevulinic acid (ALA)and porphobilinogen are excreted in the urine. Thesefeatures have given rise to speculation about possibleaetiological relationships between overproduction of por­phyrin precursors and the clinical manifestations.'"

Previous experimental studies indicated that both ALAand porphobilinogen were innocuous substances,'" but thequestion has recently been receiving further attention.On the one hand, ALA and porphobilinogen have nowbeen shown to be capable of affecting neurotransmissionin vitro:'· while on the other, experiments in intactanimals suggest that the blood-brain barrier is relativelyimpermeable to these compounds.'"

What is the situation in acute porphyria? There isabundant information on the urinary excretion rates ofALA and porphobilinogen during the acute attack, butdata on blood, cerebrospinal fluid (CSF) or tissue con­centrations of porphyrin precursors are scant.'·11 We haverecently had the opportunity of investigating 4 patientswith variegate porphyria during acute attacks, and reportour findings in this article.

PATIENTS AND METHODS

Patient 1A 30-year-old White married woman was admitted to

Department of Chemical Pathology, University of StelJeo­bosch, Parowvallei, CP

V. A. PERCY. M.SC.

E. C. Sl-IANLEY. M.SC.. ~r.D., M.R.C. PATH.

Date received: 6 June 1977.

B. C. SHANLEY

Tygerberg Hospital on 29 July 1975. According to infor­mation supplied by her general practitioner and family,she was known to suffer from variegate porphyria. Theillness had begun about 4 days previously. when she hadcomplained of low backache. For this sh received treat­ment with analgesics and diazepam. On the day beforeadmission she developed acute abdominal pain and herurine became dark in colour. She wa brought to hospitalthe next day after a convulsion and subsequent deterio­ration in her mental condition.

On admission she was stuporous. 0 localizing neuro­logical sign were present. The Watson-Schwartz test forurinary porphobilinogen was strongly positive. Her plasmasodium concentration was 114 mmol/l. Symptomatic treat­ment with Pethilorfan (Roche), chlorpromazine, diazepamand intravenous fluids was instituted.

The patient first came to our notice on the seventhday after admis ion. At this tage she was still com­plaining of abdominal pain and was mentally confused.The plasma sodium concentration had returned to normalon the third day. An electro-encephalogram indicateddiffuse cerebral changes compatible with a metabolic dis­tmb'lnce. It was repeated a week later but. although itshowed improvement. it was till abnormal. Electromyo­graphy revealed igns of a minor degree of peripheralneuropathy. By the fifteenth day the patient had improvedsufficiently to be discharged. She was subsequently seenas an outpatient, and had apparently made a goodclinical recovery.

Patient 2

A 39-year-old White married womall presented withnausea, vomiting, severe abdominal pain and constipation.She was treated symptomatically by her general practi­tioner. She improved, but about 10 days after the onsetof her illness she began to feel weak and noticed thather urine was dark. She was admitted to TygerbergHospital on 29 July 1976 with a suspected diagnosis ofacute porphyria. 0 history of previous attacks wasforthcoming. However, the patient was aware that one ofher brothers had been shown to be porphyric.

On examination she was found to have marked weak­ness of the trunk and upper and lower limb . There wasno sensory loss. She was fully conscious and well orien­tated. At this stage her respiration was not embarras ed,but she had difficulty in swallowing, speaking and cough­ing. The Watson-Schwartz test for urinary porphobilinogenwas strongly positive.

During the following few days her condition deterio­rated. She became quadriplegic, and from 2 August neededa tracheostomy and assisted ventilation. upportive therapyand tube feeding of a high-carbohydrate diet were in-

220 A MEDICAL JOURNAL 30 July 1977

stituted. Other complications requiring treatment at differ­ent times were hyponatraemia, diarrhoea, urinary infectionand bronchopneumonia. Latterly, a tracheo-oesophagealfistula developed, and was judged unsuitable for surgicalrepair. Aspiration of gastric contents ensued on severaloccasions, leading to death on 28 ovember. At autopsy,bilateral aspiration bronchopneumonia was demonstrated.

Patient 3The patient, a 30-year-old Coloured woman known to

be porphyric, had given birth to a normal infant 1month before admission to Tygerberg Hospital on 15January 1977. She had experienced a previous attack ofacute porphyria after the birth of her first child 4 yearspreviously. She complained of abdominal pain, consti­pation, weakness of the limbs and discoloration of theurine.

On examination she was found to have marked weak­ness of tbe arms and moderate weakness of the legsand trunk. Her voice was hoarse, but she had no difficultyin swallowing or with respiration. Sensation was normal.She was fully conscious and well orientated. Bullouslesions, scars and hyperpigmentation were evident on theface. the dorsa of the hands and the lower legs. TheWatson-Schwartz test for urinary porphobilinogen wasstrongly positive. She was treated symptomatically withchlorpromazine and placed on a high-carbohydrate diet.Her condition improved steadily, and at the time of dis­charge on 23 February 1977 residual motor weakness wasslight.

Patient 4A 60-year-old Coloured widow was admitted to Tyger­

berg Hospital on 29 March 1977. She had been treatedby her general practitioner, initially with penicillin andcloxacillin, for cellulitis of the lower legs. Later, co­trimoxazole had been substituted, and 10 days later shehad developed weakness of the legs and arms. No familyhistory of porphyria or of previous acute attacks wasforthcoming.

On admission she was found to have marked weaknessof both lower limbs and a lesser degree of weaknessof the arms and trunk muscles. At this stage there wasno impairment of breathing or swallowing. The patientwas fully conscious and well orientated. Sensation wasnormal, but she complained of paraesthesiae. A few scarswere evident on the dorsa of the hands and lower legs.The Watson-Schwartz test for urinary porphobilinogenwas strongly positive.

Two days after admission respiratory embarrassmentdeveloped, necessitating a tracheostomy and intermittentpositive pressure ventilation. Supportive therapy andfeeding of a high-carbohydrate diet were instituted. Othercomplications included hyponatraemia, uraemia, hypo-al­buminaemia and urinary infection. On the fourteenth dayafter admission the patient became dyspnoeic. X-rayfilms revealed pulmonary oedema and the electrocardio­gram indicated an anterior myocardial infarction. Treat­ment with diuretics and digitalis produced satisfactoryimprovement. However, a econd episode of acute pul-

monary oedema, accompanied by marked hypotension,occurred on 9 May. Despite resuscitative measures, thepatient died shortly afterwards. 0 improvement in herneurological condition had been noted at any stage.

Laboratory Investigations

Porphyrin precursors in urine were determined accordingto Mauzerall and Granick," and in serum and CSF bythe method of Marver et al.," except that in patients2, 3 and 4 porphobilinogen in serum and CSF wasmeasured using the procedure of Miyagi et al.'·' Urinaryporphyrins were analysed according to Rimington" andstool porphyrins according to Holti et al.'·

RESULTS

Representative figures for urinary and stool porphyrinexcretion are given in Table 1. The results of serialanalyses for porphyrin precursors in urine, serum andCSF are shown in Table n. The findings are consistentwith the acute attack of variegate porphyria in all 4patients.

TABLE I. URINE AND STOOL PORPHYRINS IN PATIENTSWITH ACUTE PORPHYRIA

Urine Stool

Copro ProtoUro Copro (mg/kg - (mg/kg-

(mg/I) (mg/I) dry wt) dry wt)

Patient 1 952 3173 2321 2109Patient 2 221 1637 446 1589Patient 3 2596 648 925 603Patient 4 807 206 31 136

Uro - uroporphyrin; Copro - coproporphyrin; Prota - protoporphyrin.

It was not possible to demonstrate ALA or porpho­bilinogen in the serum at any stage of the first patient'shospital stay. Likewise, neither porphyrin precursor wasdetectable in her CSF. Accordingly, it was decided to usethe more sensitive method of Miyagi et al.H for the analy­sis of porphobilinogen in serum and CSF specimens forpatients 2, 3 and 4. The highest serum level of porpho­bilinogen (2,77 mg/I) was found on the second day afteradmission, and the highest level of ALA (1,17 mg/I) on theninth day, in patient 2. Two lumbar punctures were per­formed on this patient, the first on the day of admissionand the second on the eighth day. The CSF concentrationof ALA and porphobilinogen was found to be very muchlower (33,3 and 4,5 times respectively) than in serumsampled concurrently. Similar findings were obtained inpatients 3 and 4.

DISCUSSIONAll 4 patients described had clear-cut attacks of acuteporphyria, although the manifestations in patient 1 weresomewhat different from those in the other 3. Apartfrom the abdominal symptoms, patient 1 had pronouncedencephalopathy with minimal neuropathy, whereas the

30 ] ulie 1977 SA MEDIESE TVDSKRIF 221

TABLE 11. PORPHYRIN PRECURSOR CONCENTRATIONS IN BODY FLUIDS OF PATIENTS WITH ACUTE PORPHYRIA

Urine Serum CSF

Patient 1

Patient 2

Patient 3

Patient 4

PBG = porphobilinogen.

Days afteradmission

789

10131417

1234567

89

101112131415

56789

1011

345679

1011

12

ALA(mg/I)

383733898431

3325

78

16385231

71714831

9138

15966

13391024

910545

PBG(mg/I)

523643666836

72501448

73834253214181031

152313221410

7

2617549959156394244

ALA(mg/I)

<0,5<0,5<0,5<0,5<0,5<0,5<0,5

0,40

0,601,131,170,740.350,330,250,170,02

0,420,490,610,620,67028

0,630,230,380,600,700,640,650,47

PBG(mgjl)

<o.s<0,5<0,5<0,5<0,5<0,5<0,5

1,812,771,721,602,411,791,241,431,610,990,990,600,380,260,05

0,981,000,760,941,130,59

2,122,061,401,994,095,664,713,71

ALA(mg/I)

<0,25

0,035

<0,016

<0,016

PBG(mg/I)

<0,25

0,25

0,32

0,07

0,21

main feature in the other patients was severe neuropathywithout encephalopathy. It is difficult to envisage how thesevery different clinical presentations could result fromelevated IE.vels of porphyrin precursors in the blood. Radi­cal differences between individuals with respect to uptakeof circulating ALA and porphobilinogen into the variousparts of the nervous system do not seem nry likely.On the other hand, it has been suggested that encephalo­pathy in acute porphyria may be due to water intoxication,possibly resulting from inappropriate secretion of anti­diuretic hormone and other factors, and is thereforecausally unrelated to the neuropathy. This is a plausible

9

hypothesis, but it is by no means applicable to all cases."It is noteworthy that, of our 4 patients, patients 1, 2and 4 demonstrated moderate-to-severe hyponatraemia atsome stage of their illness, yet encephalopathy was a featurein patient 1 only.

Experimental studies have shown that the blood-brainbarrier is relatively impermeable towards ALA and por­phobilinogen in normal animals or in animals pretreateuwith phenobarbitone.""" We have found that maximalbrain concentrations of ALA and porphobilinogen in ratafter intraperitoneal administration are approximately 4­8 0

;' of maximal blood levels.'" The findings in the present

222 A EDICAL JOUR tAL 30 July 1977

study suggest that the situation in patient with acute por­phyria i comparable. In patients 2, 3 and 4 the CSF:serum ratio for ALA and porphobilinogen ranged from<0,03 to 0,22. Similar result have been reported pre­viously.'o",

The concentrations of ALA and porphobilinogen foundin the C F of the 4 patients described were very low,despite the fact that they showed definite involvement ofthe nervous ystem at the time of ampling. The maximumconcentration of porphobilinogen recorded (patient 2) wa0,32 mg/I (0,0014 mM). At thi time the ALA levelwas 0,035 mgjl (0,0003 mM). These concentrations arewell below those required to produce effects on neuraltissue in vitro.""" Similar findings have been reportedby other authors in patients with acute intermittent por­phyria.'·'"

It may be argued that the C F level does not reflectthe level of porphyrin precursors in nervous tissue. Thisis naturally extremely difficult to evaluate in man, andno reliable information is available at present. Unfor­tunately, it was not possible to obtain fresh tissues atautopsy from the 2 patients who died. Experimentalevidence has shown that ALA or porphobilinogen, wheninjected intraventricularly in rats. is readily taken up bybrain tissue, but does not accumulate there.'·s If it isassumed that a partial block in neural haem biosynthe isexists in patients with acute porphyria. as we have sug­gested,'" would this not lead to accumulation of ALA andporphobilinogen in the nervous system? ot necessarily!Studies in our laboratory have shown that the activity ofthe haem biosynthetic pathway in normal mammalianbrain is very much less than in liver, and the rate-limitingenzyme, delta-aminolaevulinate syntheta e. does not appearto be inducible in brain.'· Any excess ALA or porpho­bilinogen produced in neural tis ue or entering from thecirculation would probably be slight, and if not meta­bolized, could be expected to diffuse into the extracellularfluid and thence into the CSF.

It must also be pointed out that the intraventriculardosage of these precursors required to produce clinicallyobservable effects in animals is high (2 p.mol or more),and the associated brain concentrations are of the orderof 0,4 mmol/kg S Furthermore, the effects produced bearlittle relation to the neuropathic syndromes seen in acuteporphyria.'

The evidence obtained in the present study, therefore,while not conclusive, casts considerable doubt on thepossibility that ALA or porphobilinogen is responsible forthe production of the neurological manifestations of acuteporphyria. In our view it is more probable that the symp-

tomatology of the acute attack is due to a metabolicdefect in haem biosynthesi in neural tissue, which isaggravated in ome way by precipitating factors, uchas barbiturate drugs. Thi hypothesis has been fully dis­cussed elsewhere'· and consequently will only be brieflyrecounted here. It is suggested that the metabolic, pre­sumably enzymi:::, defect in the hereditary hepatic por­phyrias is present within all cells, including those of thenervou system. nder certain conditions, such as ad­ministration of drugs known to precipitate acute attacks,a functional deficiency of haemoprotein in the neurons orglial cells or both develops and, if severe enough, leadsto degeneration and death of cells. This would becomemanifest initially as disturbed neural function and ulti­mately as axonal degeneration with econdary demyeli­nation, or primarily a demyelination, depending uponwhether neurons or glial cells were most affected. Furtherstudies based on the latter hypothesis promise to be mostrewarding in elucidating the mysteries of the acute attackin the hereditary hepatic porphyrias.

This work was supported by the South African MedicalResearch Council. We wish to thank Profe sor M. A. de Kock,Or W. J. C. J. Rosenstrauch and Or B. de Vaal for affordingus the opportunity of investigating their patients, and MrsF. Swan and Mrs A. van der Wait for technical assistance.

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