Foetor hepaticus

Penicillamine neurotoxicity: an hypothesis

Penicillamine, dimethyl cysteine, thiovaline, remains the drug of choice for the treatment of patience with Wilson disease. It is also of value in the treatment of cysteinuria and rheumatoid arthritis, it has also been suggested that it has value in the management of other rare diseases. It also has multiple toxicities. The majority of these can be explained as chemical toxicity, for instance its weak antipyridoxine action and its ability to interfere with lysyloxidea resulting in skin lesions. More important are its ability to induce immune reactions such as SLE, immune complex nephritis, the Ehlers Danlos syndrome and Goodpasture's syndrome. However the sudden increase in neurological signs which may occur in a small number of patients remains unexplained. The theory is proposed that this is due to lethal synthesis. In susceptible patients the–SH radical is liberated from penicillamine and will inhibit–SH dependent enzymes in the Krebs cycle leading to death in neurones. Other toxic metabolites may also be produced such as methyl mercaptan and ethyl mercaptan either of which could produce a similar metabolic block.

Trimethylamine and foetor hepaticus

BACKGROUND

In patients with various degrees of hepatocellular failure and portosystemic shunting of blood, the breath may acquire a sweet, musty, or even slightly faecal aroma, termed foetor hepaticus, which has been attributed mainly to volatile sulphur compounds with contributions from various nitrogenous substances. Not infrequently in such patients, unusual body odours are also encountered and, by analogy with the 'fish-odour syndrome' known to be caused by excessive trimethylamine, the availability of this latter graveolent amine to potentially contribute to odours associated with hepatic disease was investigated.

METHODS

Urine (0-24 h) was collected from 63 patients with various liver diseases previously confirmed in hospital by means of various biochemical, immunologic, pathologic, and radiologic investigations. Total trimethylamine and trimethylamine N-oxide levels in urine were measured with head-space gas chromatography.

RESULTS

In total, 50% (32 of 63) of the patients (primary liver disease, 25 of 47, or 53.2%; secondary liver disease, 7 of 16, or 43.8%) had urinary trimethylamine levels greater than the upper end of the range considered normal (0.08-1.84 microg/ml). Seventeen patients excreted large amounts of free trimethylamine (more than 10 microg/ml), above the threshold usually associated with the appearance of a 'fish-like' body odour and tainted breath.

CONCLUSIONS

Excessive amounts of trimethylamine may well contribute to the overall body odour problems encountered among patients with severe hepatic disease, precipitating in these individuals a secondary form of the 'fish-odour syndrome'.

Clinical application of breath analysis for dimethyl sulfide following ingestion of DL-methionine

After overnight-fasting, the concentration of dimethyl sulfide in expired alveolar gas (alv-DMS) was determined serially following ingestion of 2 g of DL-methionine in normal subjects and patients with liver diseases. Alv-DMS rose to a peak in 30 to 90 min, declined markedly within 3 h, and then decreased gradually. Half-disappearance times (T 1/2) (mean +/- S.E. min) in each experimental group were: normal (N = 9) 61.7 +/- 4.7, acute hepatitis (N = 6) 62.5 +/- 6.8, chronic hepatitis (N = 10) 84.0 +/- 13.0, and liver cirrhosis (N = 13) 159.2 +/- 30.4, respectively. Cirrhotics had a T 1/2 significantly longer than that of the other three groups: vs. normal P less than 0.02, vs. acute hepatitis P less than 0.05, and vs. chronic hepatitis P less than 0.05. T 1/2 of alv-DMS following ingestion of DL-methionine seems to be of clinical interest.

Serum methionine: its rapid determination by continuous-flow colorimetry

A rapid automated method for the determination of serum methionine is presented for use with the Technicon AutoAnalyzer system. It is based on the decolorisation of halide platinates by organic sulphides, including methionine. The 5--95% reference range from 249 sera from hospital patients (excluding those with liver and renal diseases and diabetes) was 20--60 mumol/l, mean 35 mumol/l. The S.D. of the method for 40 duplicate samples was 2.2 mumol/l. Recoveries ranged from 101--105%. This measurement facilitates the clinical evaluation of liver disease, especially acute liver failure, kidney disease and diabetes mellitus.

Evaluation of volatile sulfur compounds in the expired alveolar gas in patients with liver cirrhosis

Trace amounts of volatile sulfur compounds were determined in the expired alveolar gas by gas chromatography. Among these sulfur containing substances, methyl mercaptan and dimethyl sulfide were quantitatively analyzed in 116 subjects; 53 normal, 13 acute hepatitis, 11 chronic hepatitis, 20 hepatic cirrhosis, and 19 stomach ulcer and/or biopsy of gastric mucosa. Fasting level of dimethyl sulfide in cirrhotics was 4.05 +/- 1.06 ng/dl, significantly elevated by comparison with normal controls (1.54 +/- 0.09 ng/dl) (P less than 0.05). In contrast, methyl mercaptan did not show a statistically significant rise in this study. The implications of the significant increase in dimethyl sulfide concentration in liver cirrhosis are discussed.

Urinary and serum octopamine in patients with portal-systemic encephalopathy

Urinary excretion and serum concentrations of octopamine were studied in seventeen controls, thirty-three patients with portal-systemic encephalopathy, and thirteen patients with liver disease without encephalopathy. No differences were detected between control subjects and patients without encephalopathy. Urinary excretion and serum concentrations of octopamine were significantly higher in patients with encephalopathy compared with those without encephalopathy. The presence and grade of portal-systemic encephalopathy seemed to correlate more closely with the serum-octopamine concentrations than with urinary octopamine excretion. It is postulated that octopamine may be involved in the pathogenesis of portal-systemic encephalopathy.

Methionine-induced hepatic coma in dogs

Oral methionine is noncomatogenic in normal dogs, but it is consistently comatogenic in dogs with portacaval shunts in the presence of elevated ammonia levels. Such action appears to be enhanced by the ammonia itself, since relatively small doses of oral methionine can induce coma when baseline levels of ammonia are above 1,000 mug/100 ml; much higher doses are nesessary for near normal ammonemia. The methionine-induced coma closely reproduces the clinical and electroencephalographic picture of coma in other canine models. Oral methionine does not significantly increase the ammonia levels, but its action is probably mediated by the release of methanethiol (and other less active compounds) from the bowel. Methanethiol levels tend to increase in proportion to the amount of methionine administered, and its comatogenic action may be amplified, up to one hundredfold, by high ammonia levels. Methanethiol levels in comatose patients and the concept of the synergistic effect with ammonia may lead to a clearer understanding of certain enterogenous and dietetic forms of hepatic encephalopathy in cirrhotic patients. The lowering of ammonia levels by hemodialysis or methanethiol levels by activated charcoal hemoperfusion, as attempts to reverse such forms of coma, warrants further investigation.