RxPG - Hemochromatosis

Definition

Hemochromatosis is a disease due to increased iron absorption that leads to accumulation of iron in diverse tissues.

Classification

It can be hereditary (primary hemochromatosis) or secondary to chronic anemias as ß-thalassemias (ineffective erythropoiesis leading to increased erythrocitic destruction) or defects in hemoglobin synthesis ( as in porphyria cutanea tarda) ;multiple transfusion therapy ;or others less common conditions.

Pathogenesis

Iron absorption from the gut occurs normally in a rate of 1 mg per day. In hemochromatosis this absortion reaches the rate of 4 to 5 mg/d and there is a progressive accumulation to 15 to 40 grams of body iron (normal ~ 2 to 3 g). Thus, the disease develops in men above age 20 and postmenopausal women, due to stopping in iron loss in menses. The iron accumulates in every tissue of the body, but main clinical manifestations are secondary to iron deposition in: Liver, thyroid, hypothalamus, heart, pancreas, gonads and joints.

Clinical Manifestations

Many patients are asymptomatic. Common symptoms are fatigue, arthalgias, impotence, amenorrhea and palpitations. The most characteristical clinical manifestation occur in the liver because the portal circulation filters the iron initially absorbed fom the gut. Usually patients develop cirrhosis. Heart manifestations include arrythmias and disturbances of conduction. Skin adquires an diffuse hyperpigmentation mainly in scars, sun exposed and unexposed areas and genitalia. Arthropathy occurs in wrists, hips, knees and ankles. To distinguish this arthopathy from others, searching for initial involvement of second and third metacarpophalangeal joints is helpful. Hypogonadism hipogonadothrofic is secondary to iron deposition in hypophisary cells and leads to loss of libido, amenorrhea, impotence and body hair losing. Diabetes Mellitus results from pancreatic accomitment and the signs and symptons, as the treatment, do not differ from conventional diabetes.

Diagnosis

The diagnosis is made on high index of suspicion. Any patients presenting with unexplained hepatomegaly, cardiac insuficiency or arrhythimias, arthritis, diabetes mellitus, hyperpigmentation or hypogonadism hipo gonadothrofic should be investigated for hemochromatosis.

Serum transferrin saturation and ferritin levels are the initial tests of choice, since they toghether are highly sensitive and especific, even in the initial phase (named precyrrhotic phase), when there are no symptons. However, they must be interpreted as screening tests. Indeed, ferritin may rise if hepatocellular inflamation or necrosis occurs. When one of these tests is positive, liver biopsy should be carried out, since this is the only way to establish a definitive diagnosis. When liver biopsy is not feasible, an iron excretion test with deferoxamine (an iron chelant) may have diagnostic implications. Computed Tomography (CT) and Nuclear Magnetic Ressonance (NMR) show a diffuse increase in hepatic density, but the sensitivity of these tests is still under investigation.

Treatment

Phlebotomy, made weekly or twice weekly, is the treatment of choice. It can remit almost all manifestations, with the exception of arthropaty and hypogonadism. It should be clear that once cirrhosis is established, it is untreatable and a 30% risk of hepatocellular carcinoma occurs. Phlebotomy consists on a 500 ml of blood extraction.

When severe anemia or hipoproteinemia exists, phlebotomy is contraindicated. In these cases, treatment with deferoxamine, although not as effective as phlebotomy, may relieve symptons.

Prognosis

Life expectancy rises from 33 to 89% if untreated patients are compared with patients treated with phlebotomy. Patients whom the disease is detected early may actually have a normal life expectancy and quality. It should be emphasized that a late diagnosis may implicate in untreatable arthropaties, hypogonadism, cirrhosis and hepatocellular carcinoma.