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Chapter 11: Adrenal axis 437

Table 11.9 Abnormalities of the adrenal axis
Increased hormone Decreased hormone
CRH Cushing’s disease
CRH-secreting tumour (very rare)
ACTH Cushing’s disease Hypopituitarism
(ACTH-secreting pituitary tumour)
Addison’s disease
Nelson’s syndrome
Mineralocortic oids Primary hyperaldosteronism (adenoma or hyperplasia) Adrenocortical insufficiency
Secondary hyperaldosteronism
Glucocorticoids Cushing’s syndrome Adrenocortical insufficiency
Causes include nodular hyperplasia, adrenal cortex tumour
Androgens Congenital adrenal hyperplasia Adrenocortical insufficiency
Also hyperplasia and tumours

Pain, stress, hypoxia, cold, hypoglycaernia
depression
Oxytocin
+ −
Hypothalamus
CRH −

+
Anterior Pituitary ACTH −

Adrenal Glands
(Cortex)

Outer zona glomerulosa Inner zona fasciculata and zona reticularis

Mineralocorticoids Androgens Glucocorticoids
(Aldosterone) (Cortisol)
Figure 11.8 The adrenal axis.

are also secreted by the gonads (see Fig. 11.8 and When aldosterone levels are high this may be due to
Table 11.9). high renin levels (secondary hyperaldosteronism) or it
may be independent of renin production (primary hy-
Aldosterone peraldosteronism).
Aldosterone is the corticosteroid with the most min-
eralocorticoid activity, so-called because it controls Cortisol
sodium, potassium and water balance. Its production Cortisol is the major glucocorticoid, although aldos-
is stimulated mainly by the renin–angiotensin system. terone and corticosterone also have some effect. The glu-
Renin is secreted from the juxtaglomerular apparatus in cocorticoids control glucose metabolism, for example
the kidney in response to reduced renal blood flow, for gluconeogenesis, and mobilisation of fat stores (lipol-
example due to hypotension. In response aldosterone ysis) amongst other actions. Cortisol exerts a negative
acts on the kidney and vasculature (see Fig. 11.9). feedback on ACTH and CRH secretion. Glucocorticoids