Endocrine Abstracts

We report the case of a 74 year old woman, admitted as an emergency with suspected pelvic malignancy in whom the clinical features and the positive tumour markers were actually due to hypothyroidism. The presenting features included cachexia, anorexia and severe ascites. Vital signs were normal. Examination revealed bilateral pleural effusions but no abdominal masses were palpable. Rectal examination was unremarkable. Investigations showed an extremely elevated CA 125 level of 1059 U/ml (< 37), which supported the diagnosis of ovarian carcinoma. Diagnostic and therapeutic paracentesis revealed an exudate (protein 37 g/l) however there were no malignant cells. In addition, computerised tomography of the abdomen and a diagnostic laparoscopy showed no evidence of intra-peritoneal malignancy. Although the patient was not clinically overtly hypothyroid, we performed thyroid function tests because of her hoarse voice and dry skin. These revealed profound biochemical primary hypothyroidism with a serum thyroid stimulating hormone level of 73 mU/l (0.2 to 5.7) and free thyroxine of 5 pmol/l (9 to 19). The thyroid peroxidase antibodies were positive at a titre of 806 IU/ml (< 50). She was started on thyroxine replacement therapy. Over the next 8 weeks, her condition improved gradually with restoration of the euthyroid state.

In the only similar reported case of myxedematous ascites, there was a moderate elevation of CA 125 (684 U/ml), which normalised when the patient became euthyroid with thyroxine replacement. In our case, CA 125 levels fell to normal swiftly with draining of ascites whilst the patient remained biochemically hypothyroid. Thus, we suggest that the mechanism of extreme elevation of CA 125 levels in myxedematous ascites is the peritoneal irritation caused by the ascites rather than hypothyroidism itself.

In summary, this is an uncommon presentation of profound hypothyroidism mimicking pelvic malignancy. It also illustrates that extreme elevation of CA 125 levels can occur in benign conditions including hypothyroidism in the presence ascites.