PLASMA SOMATOSTATIN CORRELATES WITH BLUNTED THYROTROPIN SECRETION AFTER STIMULATION BY THYROTROPIN-RELEASING-HORMONE IN CRITICAL ILLNESS

To clarify whether plasma somatostatin affects thyrotropin secretion i n critical illness, plasma somatostatin and thyrotropin responses to t hyrotropin-releasing hormone were studied in forty-three critically il l patients. High somatostatin levels were associated with blunted thyr otropin secretion in clinically ill patients. There was an inverse cor relation between plasma somatostatin levels and the maximum increment of thyrotropin after stimulation by thyrotropin-releasing hormone. Dec reased somatostatin and increased thyrotropin secretion before dischar ge from the intensive care unit were demonstrated in survivors. On the other hand non-survivors maintained high somatostatin levels and had blunted thyrotropin secretion during their intensive care admission. T hese results suggest that high plasma somatostatin levels may play a r ole in the blunted thyrotropin secretion observed in critical illness.