Makindo Medical Notes

Related Subjects: |Adrenal Physiology |Addisons Disease |Phaeochromocytoma |Adrenal Adenomas |Adrenal Cancer |Cushing Syndrome |Cushing Disease |Congenital Adrenal hyperplasia |Primary hyperaldosteronism (Conn's syndrome) |ACTH |McCune Albright syndrome |Male Infertility |Prolactin |Prolactinoma |Sheehan's syndrome

It is very important to maintain and increase steroids (at least double the dose) during stress events like infections, surgery, trauma, or illness. In suspected but undiagnosed hypopituitarism in an unwell patient, it’s best to administer steroids first and address diagnosis later.

About

• The anterior pituitary releases six key hormones: LH, FSH, GH, TSH, ACTH, and Prolactin.

Causes

• Pituitary adenoma: May be non-functioning or hormone-secreting (e.g., prolactinoma).
• Craniopharyngioma: Typically seen in children.
• Infiltrative diseases: Sarcoidosis, tuberculosis, haemochromatosis.
• Vascular causes: Sheehan's syndrome (postpartum) and pituitary apoplexy (acute onset).
• Infectious: Meningitis, encephalitis, syphilis.
• Trauma: Especially basal skull fractures.
• Congenital: Kallmann syndrome (GnRH deficiency + anosmia).
• Autoimmune: With pituitary antibodies.
• Other causes: Anorexia, starvation, radiation damage, chemotherapy.

Clinical Presentation

• ACTH deficiency: Reduced cortisol levels; mineralocorticoids are preserved (unlike Addison’s disease).
• Prolactin deficiency: Reduced ability to lactate; elevated levels may indicate pituitary stalk compression.
• LH, FSH deficiency: Infertility, decreased libido, amenorrhoea, or impotence.
• GH deficiency: Short stature (pre-epiphyseal fusion); in adults, low muscle bulk and energy.
• TSH deficiency: Leads to hypothyroidism.
• ADH deficiency: Can cause cranial diabetes insipidus if posterior pituitary is compressed.

Local Effects of Pituitary Lesions

• Headache.
• Bitemporal hemianopia (visual field loss).
• Deficiency of pituitary hormones.
• Cranial nerve palsies (III, IV, VI).

Investigations to Assess Pituitary Function

• Serum prolactin, TSH, T4, and 9 am serum cortisol.
• Serum IGF-1 and GH, FSH, LH, oestrogen, and testosterone.
• Fasting blood glucose and HbA1c.
• Pituitary MRI.

Management

• Acute cases: In suspected acute hypopituitarism, initiate IV hydrocortisone 100 mg every 6 hours.
• Hydrocortisone: Oral doses of 15-40 mg per day (usually 15 mg in the morning and 5 mg in the afternoon).
• Thyroid replacement: Administer L-thyroxine, adjusting to maintain normal T4 levels (not TSH).
• Gonadotropins:
  • Males: Testosterone replacement (IM, oral, transdermal, or implant) if fertility is not desired. Gonadotropins if fertility is desired.
  • Females: Oestrogen-progesterone therapy if fertility is not desired; gonadotropin therapy or pulsatile GnRH if fertility is desired.
• Growth hormone: Not typically needed in adults, as GH administration may increase malignancy risk.