Syndrome of apparent mineralocorticoid excess

Syndrome of Apparent Mineralocorticoid Excess (SAME) is a rare autosomal recessive genetic disorder that is characterized by hypertension and hypokalemia. The syndrome is caused by mutations in the HSD11B2 gene, which encodes the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2). This enzyme is responsible for the conversion of cortisol to its inactive metabolite, cortisone. In the absence of this enzyme, cortisol can bind to mineralocorticoid receptors and mimic the action of aldosterone, leading to an apparent excess of mineralocorticoid activity.

Clinical Features

Patients with SAME typically present in infancy or early childhood with severe hypertension, hypokalemia, and metabolic alkalosis. Other features may include failure to thrive, polyuria, polydipsia, and muscle weakness. In severe cases, patients may develop cardiac hypertrophy and renal failure.

Diagnosis

The diagnosis of SAME is based on the clinical features and biochemical findings, including low levels of aldosterone and renin in the presence of hypertension and hypokalemia. Genetic testing can confirm the diagnosis by identifying mutations in the HSD11B2 gene.

Treatment

Treatment of SAME involves the use of potassium-sparing diuretics and corticosteroids to reduce the effects of cortisol on the mineralocorticoid receptors. In severe cases, adrenalectomy may be considered.

Prognosis

The prognosis for patients with SAME is variable and depends on the severity of the disease and the response to treatment. With early diagnosis and appropriate treatment, the prognosis can be favorable.

See Also

• Hypertension
• Hypokalemia
• Genetic disorders
• Autosomal recessive