Hemochromatosis (Bronzed Diabetes): Pathogenesis, Clinical Manifestations, Prognosis, Diagnosis And Treatment
A General Overview
This is a metabolic disorder associated with marked increase in iron store in the body. Two forms are known, the idiopathic type, an autosomal dominant or recessive disorder in different families and the secondary type due to iron overload. HLA.A3 and B14 are more frequently associated with idiopathic hemochromatosis. The condition has been reported from India.
Pathogenesis: The main defect is loss of regulation of intestinal absorption of iron resulting in increased absorption of dietary iron. This iron is taken up by several parenchymal tissues and macrophafes which results in toxic damage. The pathological changes include cellular dysfunction, necrosis and fibrosis. Liver and pancreas are most severely affected. The skin, myocardium and endocrine glands like the adrenal cortex, tests and thyroid are affected with varying severity. The condition remains asymptomatic till the total body stores of iron reach 15 to 20g.
The liver is enlarged firm to hard in consistency, and the cut section is brown. The hepatocutes and kupffer cells show stainable iron. Eventually, portal cirrhosis develops. Acinar cells of the pancreas and less frequently the islet cells show hemosiderin. Diabetes may develop. There is increase in iron in several organs. Skin shows increased pigmentation due to deposition of melanin.
Melasma Or Hemochromatosis
Clinical Presentations And Treatment
Males are affected five times more frequently than females. Symptoms generally start in the fourth and fifth decades. These include lethargy, loss of libido and impotence, pigmentation, hepatomegaly and diabetes. Cirrhosis of liver and testicular atrophy occur in advanced cases. Severity of the diabetes is variable. Cardiac enlargement, cardiac failure and arrhythmias occur in 10- 15% of cases. Arthropathy develops due to deposition of calcium pyrophosphate and hemosiderin in the synovium. In long standing cases, hepatocellular carcinoma may develop.
Course and Prognosis: Mean survival in untreated cases is 5 years after diagnosis. Death is caused by infection, cardiac failure, hepatic failure, hepatic carcinoma or diabetic complications. Modern treatment has improved the outcome considerably.
Diagnosis: Hemochromatosis should be considered in all patients presenting with hepatic cirrhosis, diabetes, skin pigmentation and cardiac abnormalities. In hepatic cirrhosis, there is accumulation of iron in liver and this should be distinguished from primary hemochromatosis. Serum Iron is usually above 175 ug/dl, TIBC is 200 ug/dl and transferring saturation is almost 100%. Serum ferritin may be increased to 1000 ng/ml in severe cases and in the absence of significant hepatocellular damage, this reflects the enormous iron load.
The 24 hour urinary excretion of more than 2 mg iron following intramuscular injection of 0.5g of desferrioxamine is suggestive of excessive iron stores. Values greater than 10 mg indicate idiopathic hemochromatosis. Liver biopsy shows excess iron deposition.
Simple venesection to remove 500 ml blood once in two weeks helps to prolong life to a mean of 8 years and improves hepatic function. The hematocrit is adjusted to around 35% by venesection. Each venesection removes 250 mg of iron. When the iron stores become normal, cirrhosis may regress and the pigmentation may come down. Diabetes is controlled on its own merits. The Iron chelating agent desferrioxamine has been used when venesection is contraindicated by the presence of anemia, but the drug is less effective.
© 2014 Funom Theophilus Makama