Box 13.1 Causes of hypopituitarism

Pituitary a denomas

Other tumours/cysts

Craniopharyngiomas, meningiomas, malignant tumours (germ cell tumours, chordoma, sarcoma), pituitary metastases (e.g. lung, breast), cysts (e.g. Rathke’s cleft)

Pituitary/hypothalamic surgery

Trauma (basal skull fracture)

Pituitary/hypothalamic radiation

Infarction

Apoplexy, Sheehan’s syndrome

Inflammation/infiltration/infection

Lymphocytic hypophysitis, sarcoidosis, haemochromatosis, Langerhans cell histiocytosis, tuberculous meningitis

Genetic

e.g. PROP1 or PIT1 mutations

Clinical presentations

Signs and symptoms resulting from various pituitary hormone deficiencies are summarized below.

GH deficiency

GH deficiency can result in fatigue, impaired psychological well-being, reduced energy, muscle strength and exercise capacity, and increased abdominal adiposity (fat mass).

LH and FSH deficiency

LH/FSH deficiency in men results in secondary hypogonadism: reduced libido, oligospermia and infertility, loss of body hair, fine perioral wrinkles, flushes and osteoporosis (see Chapter 19).
LH/FSH deficiency in women results in secondary hypogonadism: oligomenorrhoea/amenorrhoea, infertility, dyspareunia, breast atrophy, hot flushes and osteoporosis (see Chapter 21).

ACTH deficiency

ACTH deficiency results in secondary adrenal insufficiency: fatigue, weakness, nausea, vomiting, weight loss, hypoglycaemia and loss of pubic and axillary hair in females (see Chapter 6).

TSH deficiency

TSH deficiency results in secondary hypothyroidism: fatigue, apathy, muscle weakness, cold intolerance, constipation, weight gain and dry skin (see Chapter 2).

Antidiuretic hormone deficiency

Antidiuretic hormone (ADH) deficiency results in diabetes insipidus: polyuria, nocturia and polydipsia (see Chapter 17).

Prolactin deficiency

The only known presentation of prolactin deficiency is the inability to lactate after delivery.

Investigations

Pituitary function tests and pituitary imaging are discussed in Chapter 12.

Treatment and monitoring

ACTH deficiency

Hydrocortisone is the logical option for glucocorticoid replacement because it is the glucocorticoid normally made by the adrenals. A daily regimen of 10 mg in the morning, 5 mg at noon and 5 mg in the evening is probably the ‘best-guess’ starting dose. Cortisol has a plasma half-life of less than 2 hours. The traditional hydrocortisone regimen of 20 mg in the morning and 10 mg in the evening is suboptimal for two reasons. First, it may result in low cortisol levels and low quality of life scores in late afternoon. Second, hydrocortisone production rates in normal individuals are lower than previously believed. Chronic over-replacement (>20 mg per day) may result in Cushing’s syndrome.

It is essential that patients are provided with:

information regarding doubling of hydrocortisone dose at times of intercurrent illness
an emergency intramuscular hydrocortisone supply (to be given at times of vomiting on their way to hospital)
a steroid card and MedicAlert bracelet.

Glucocorticoid replacement may unmask underlying central diabetes insipidus, leading to marked polyuria.

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