Endocrine Abstracts

Although pituitary abnormalities are the most commonly reported endocrine feature in septo-optic dysplasia, other endocrine abnormalities have not been described so far. We present a case of septo-optic dysplasia (SOD) and pituitary dysfunction, complicated by X-linked adrenoleucodystrophy (X-ALD) and primary adrenal insufficiency.

A 4-year-old boy was referred with hypoglycaemic episodes and seizures during intercurrent illnesses. He had a history of polyuria and polydipsia. Clinical assessment revealed congenital nystagmus, right-sided hemiparesis and delayed early speech. Endocrine work up revealed a low cortisol concentration of 79 nmol/l (ref. 80–580 nmol/l). A subsequent short synacthen test showed a flat cortisol response (maximum cortisol value at 60 min was 75 nmol/l) suggesting adrenal insufficiency. Paired plasma osmolality (290 mmol/kg) and urine osmolality (87 mosmol/kg) indicated diabetes insipidus (DI). IGF1, TSH and Gonadotrophin levels were however normal. MRI Brain showed characteristic changes of SOD.The diagnosis of hypopituitarism secondary to SOD was made.

However, the ACTH level was found unexpectedly to be elevated at 593 ng/l (ref.<46 ng/l). An incidental finding of increased very long chain fatty acids (VLCFA) gave the diagnosis of X-ALD. He was thereafter shown to be hemizygous for the p.(Arg660Trp), c.1978>T mutation in exon nine of the ABCD1 gene, a previously described mutation in X-ALD affected individuals. There was a maternal family history of late onset neurological problems.

Thus, the very rare possibility of co-existence of two separate conditions was raised–i) septo-optic dysplasia leading to posterior pituitary dysfunction and hence DI and ii) X-linked ALD leading to primary adrenal insufficiency.

The child is now being treated with desmopressin for DI, replacement doses of hydrocortisone for adrenal insufficiency and Lorenzo oil for XALD. MRI scans show no white matter changes of X-ALD and will be repeated 6 monthly.

We believe that this is the first reported case of SOD and X-ALD.