Endocrine Abstracts

A 54-year-old man with long standing coeliac disease and moderate dietary compliance was admitted with lethargy and feeling unwell. His blood pressure was 129 mmHg systolic, 91mmHg diastolic and serum sodium 112 millimoles per litre (RR 136 to 145). He was otherwise well with normal visual fields. A 250-microgram Synacthen test demonstrated a basal cortisol of 630 nanomoles per litre rising to 983 nanomoles per litre after 30 minutes. His TSH was undetectable, Ft4 9.6 picomoles per litre (RR 10 to 25). A pituitary MRI demonstrated a 3mm microadenoma only. He improved with fluids and was discharged but was readmitted 2 weeks later with similar symptoms, blood pressure 100mmHg systolic, 60mmHg diastolic, serum sodium 123 millimoles per litre, TSH undetectable, Ft4 5.9 picomoles per litre. A 1-milligram Glucagon stimulation test demonstrated no response with all cortisol levels less than 55 nanomoles per litre. He transferred to the endocrinology unit and hydrocortisone was started. His testosterone was 2.4 nanomoles per litre (RR 8.0 to 27.0), SHBG 99 nanomoles per litre (RR 15 to 55), LH and FSH 2.4 and 6.0 international units per litre respectively and prolactin normal. LFT's were normal. His ferritin was 619 micrograms per litre (RR 20 to 300) having been 369 micrograms per litre in 1999 and iron and transferrin levels were elevated with a transferrin saturation of 86 percent. Genotyping confirmed homozygosity for the C282Y mutation of the HFE gene. Repeat MRI confirmed a micro-incidentaloma but T2 FE and T2GE scanning did not show elevated pituitary iron levels.

We hypothesise this hypopituitarism is secondary to haemochromatosis. In failing to maintain a strict gluten free diet we surmise the accumulation of iron was retarded through malabsorption, delaying the diagnosis. This case reminds clinicians that a short Synacthen test may be falsely reassuring in hypopituitarism of recent onset.