Corticosterone methyloxydase deficiency type II in a Croatian girl.

This is a brief case report on a four-month-old girl who was admitted for failure to thrive and moderate dehydration. On admission she was mildly dehydrated and undernourished but with otherwise normal physical findings. Laboratory investigation disclosed mild but constant hyponatremia and hyperkalemia, very high plasma renin activity (greater than 900 ng/mL per hour) and low plasma aldosterone concentration (2.5 ng/dL). The plasma 18-hydroxycorticosterone (18-OH-B) was very high (1,682 ng/dL), producing thus an abnormally elevated 18-OH-B to aldosterone ratio of 542 (normally 6.3 +/- 3.6). The diagnosis of corticosterone methyloxydase deficiency type II was made, and the administration of fluorohydrocortisone resulted in rapid weight gain with normalization of blood electrolytes and gradual decrease in plasma renin activity. A very efficient catch-up growth resulted in normal body weight and length at the age of 2 years. This is the first well documented case of the disease in the population of Yugoslavia.