Endocrine Abstracts

Case History: A 60 year old female presented with anxiety and weight loss. Serum free T4 was 50 pmol/l (normal 12-23). Despite restoring T4 to normal, symptoms persisted and included flushing attacks. Urine 5-HIAA was elevated (182 micro moles/24 hrs; normal 0-40).Tests were done to locate the primary and secondary carcinoid tumour.

Investigations: CT of thorax and abdomen, and ultrasound of abdomen were negative. Routine biochemistry and haematology were normal. Gastroscopy suggested a lesion on the right side of the stomach.

Management: At laparotomy a tumour was removed from the left lobe of the liver, adjacent to the stomach. Histology confirmed a carcinoid tumour.

Progress: Carcinoid symptoms have been absent during 46 months of follow-up. However, although she remained clinically euthyroid, serum T4 became elevated at 74 pmol/l, with detectable TSH of 0.31 MU/l. The results of the endocrine assays were incompatible with clinical findings. Serum cortisol was elevated (4000 nmol/l), suggesting Cushing's syndrome. Serum testosterone of 22 nmol/l (normal 0.7-2.8), and oestradiol of 2632 pmol/l in a postmenopausal female were suggestive of an adrenal carcinoma. LH and FSH were inappropriately suppressed for the postmenopausal state (5.2 and 5.1 IU).

Review of scans showed no evidence of adrenal or ovarian tumours. Laboratory error was suspected. Heterophile anti-sheep antibodies were subsequently detected in the patient's serum. Ruthenium and streptavidin interference was absent. Tests in another laboratory using a different assay gave normal serum values- Cortisol 488nmol/l, T4 14 pmol/l, testosterone 2 nmol/l, oestradiol 72 pmol/l, LH 24.6, FSH 37 IU/L.

Conclusion. When clinical symptoms and signs do not agree with biochemical assays, consider the possibility of spurious results due to heterophile antibodies. Our patient was relieved to be cured of her carcinoid syndrome, but bemused by the sheep antibodies, which could not be explained by personal contact.