Summary
Peripheral blood leukocyte counts and plasma hormonal changes in response to acute
insulin-induced hypoglycaemia were examined in 16 patients undergoing assessment of
pituitary function. Eight subjects had a normal cortisol secretory response (Group
1), and 8 patients had definite hypopituitarism in whom the cortisol responses were
deficient or absent (Group 2). An equivalent degree of hypoglycaemia was achieved
in both groups. In Group 1a biphasic rise in leukocyte count occurred following hypoglycaemia,
with an early rise in lymphocytes at 15 minutes after the acute hypoglycaemic reaction,
and a later rise in granulocytes. A similar rise in lymphocytes was observed in Group
2, but the rise in the granulocyte count was attenuated, increasing from a basal value
of 3.6 ± 0.6 × 109 cells/L to a peak of 7.4 ± 1.1 × 109 cells/L, compared with a peak of 11.7 ± 1.2 × 109 cells/L in Group 1 (P < 0.05). The usual increment in plasma cortisol in response
to hypoglycaemia occurred in Group 1, but plasma cortisol did not rise in Group 2.
A correlation was observed between the magnitude of the granulocyte rise and the increment
in plasma cortisol in individual subjects (r = 0.64, P < 0.02). This suggests that
the rise in peripheral granulocytes following insulin-induced hypoglycaemia in man
is mediated by cortisol released from the adrenal gland, following activation of the
hypothalamic-pituitary-adrenal axis.
Key words
Hypoglycaemia - Leukocyte - Granulocyte - Lymphocyte - Cortisol - Hypopituitarism
