|Year : 1986 | Volume
| Issue : 3 | Page : 166-7,170A
Alkaptonuria (a case report).
JR Sachdeva, MM Gupta, VK Jindal
J R Sachdeva
|How to cite this article:|
Sachdeva J R, Gupta M M, Jindal V K. Alkaptonuria (a case report). J Postgrad Med 1986;32:166-7,170A
|How to cite this URL:|
Sachdeva J R, Gupta M M, Jindal V K. Alkaptonuria (a case report). J Postgrad Med [serial online] 1986 [cited 2020 Oct 22 ];32:166-7,170A
Available from: https://www.jpgmonline.com/text.asp?1986/32/3/166/5333
Alkaptonuria is a rare inborn error of metabolism of amino acid tyrosine, caused by deficiency of the enzyme, homogentisic acid oxidase, leading to accumulation of homogentisic acid. Part of this is excreted in urine. Since homogentisic acid has lot of affinity for alkalies, it was named alkapton and this condition as alkaptonuria. The rest gets polymerized in vivo and is deposited as a pigment in connective tissues of the body, mainly of the joints, but it may also be deposited in the skin, cartilages, outer eye structures, cardiovascular system and in urinary calculi. This pigment, though looks brownish black grossly, is ochre (yellow) microscopically so this pigment deposition was called ochronosis. Recently we had under our care one case of alkaptonuria which is being reported here.
A 38 year old male patient, started having slowly increasing mild pain and stiffness in the lower back for three years. The patient consulted an orthopaedic surgeon who diagnosed it as prolapsed disc and put him on analgesics, anti-inflammatory drugs, hard bed etc. This gave him some relief but on stopping the treatment, he again started having complaints of pain and stiffness over a longer area of the spine. For the past three months, the patient had pain in hip joints also. There was no history of fever, trauma, chronic cough, acute abdominal pain, dysuria or haematuria. The urine had normal colour when voided but the patient was aware of brownish black staining of underwears since childhood. About two years earlier, the patient was diagnosed as a case of diabetes mellitus on the basis of urine examination and was put on antidiabetic oral drugs. The patient went into hypoglycaemic semicoma and antidiabetic drugs were withdrawn. A grandson of his paternal uncle had similar staining of underclothes but was not available for testing of urine. There was no history of consanguinity.
Examination revealed moderately built and nourished patient having no anaemia, cyanosis, jaundice or oedema of the feet. Neck, pulse, B.P., heart, chest, abdomen, nervous system examination revealed no abnormality. Joints were mainly affected. Percussion tenderness was positive over the lumbar spine with marked limitation of movements. Lasegue's test was positive and movements at both the hip joints were limited and painful. Both the ear drums and aural cartilages showed bluish pigmentation. No pigmentation of the skin at other places or eye. structures was visible.
His haemoglobin was 13.5 gm%, total leucocyte count was 6800/cmm., with P 65%, L 32%, M 1% and E 2%. Serum uric acid was 3.5 mg%; E.S.R., 3 mm in the 1st hour; fasting blood sugar 84 mg%; and glucose tolerance tests within normal limits. Free fatty acids were 670 Ámol/L; serum cholesterol 160 mg%; and glycosylated haemoglobin 6.95%. Urine was of normal colour when voided but turned black over variable periods spontaneously; also turned black with Benedict's reagent, strong alkali and ferric chloride. It was positive for homogentisic acid by silver nitrate test and negative for glucosazone crystals. E.C.G. was normal. Mother's, father's, brother's and both sons' urine was negative for homogentisic acid. X-rays of the spine [Fig 1] revealed narrowing of disc spaces and calcification of intervertebral discs; sacroiliac joints, hip joints, and pubic symphysis were normal; no prostatic or renal calculi were seen.
Review of world literature on this condition relating to pattern of inheritance, metabolic defect, pathogenesis, clinical course and treatment has been summarized by O'Brien et al. Isolated case reports from India are also available.,,, The present case had ochronotic arthropathy, pigmentation of ear drums and pinna, calcification of discs and ear cartilage.
Alkaptonuria, though an inherited disorder yet being symptomless per se, is not usually noticed until middle life. It is usually in the fourth decade that degenerative joint disease manifests first with back pain as in our case. The fresh urine is of normal colour and darkening may occur so slowly at acid pH that the patient may be unaware. Knowledge of dark staining of underwears since childhood as in this patient is often ignored. Staining of undergarments. may be due to application of soaps (alkaline) during washing. Scleral pigmentation appears many years before arthropathy. However, it was not seen in our case.
Involvement of hip joint as a part of peripheral arthropathy occurred after more than two years of spondylosis as reported earlier by O'Brien et al. Knee joints which are considered to be the most frequent and earliest joints to be affected were completely spared in this patient.
Two interesting aspects of this case were: (1) at the onset, he was treated as a case of disc disease, and (2) he was put on antidiabetic drugs on the basis of Benedict's test of urine. He developed hypoglycaemia. Misdiagnosis of diabetes mellitus was also reported in 28 out of 252 cases reviewed by O'Brien et al and this may cost the patient his life if diagnosis of diabetes is not substantiated by blood sugar estimation.
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