Endocrine Abstracts

Acute critical illness has an effect on normal physiology resulting in changes in the inter-relations of the endocrine system.

Evidence suggests that these changes may be due to the pro-inflammatory cytokines (e.g. interleukin-6 (IL-6)), which are known to have a paradoxical effect on the hypothalamo-pituitary axis, stimulating the adrenal axis, whilst suppressing the remaining axes.

Multiple myeloma (MM) patients have elevated IL-6 levels, a product of plasma cells. The aim of this study was to examine the effects of elevated IL-6 in myeloma patients on their hypothalamic-pituitary endocrine axes before and after dexamethasone (DXT) treatment

Nine sick myeloma patients were recruited. Blood was taken between 9 and 11 am and analyzed for cortisol, ACTH, testosterone, luteinizing hormone, GH, insulin-like growth factor, thyroid-stimulating hormone, free thyroxine (FT4), free tri-iodothyronine (FT3), DXT, and IL-6 using routine assays. Another sample was taken following the commencement of DXT treatment (20-40mg daily for a mean of 5 days). Pre and post treatment levels were compared to those of healthy controls. Ethical approval was obtained.

The MM patients had significantly raised IL-6 (8.7plus/minus 2.9 (SEM) vs. 1.4 plus/minus 0.36 pg/ml p<0.05), significantly lower testosterone (6.2 plus/minus 1.6 vs. 21.5 plus/minus 1.7nmol/l p<0.01) and significantly lower FT3 levels (3.2 plus/minus 0.3 vs. 5.0 plus/minus 0.2 pmol/l p<0.0001) compared with the controls. Following DXT treatment both cortisol (55.5 plus/minus 14.7 vs 310.4 plus/minus 75.1 nmol/l p<0.01) and ACTH levels (8.4 plus/minus 2.2 vs. 28.4 plus/minus 4.3 ng/l p<0.01) were significantly lower than pre-treatment levels. The other hormone levels were not significantly different from the controls and did not change with treatment.

This study found that in chronically sick patients, IL-6 appears to have no effect on the hypothalamo-pituitary secretions but a possible effect on peripheral hormone production and metabolism. This contrasts with reported findings in acutely critically ill patients.