Makindo Medical Notes.com

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 to double) in the event of stress - infection, surgery, trauma, illness. In undiagnosed but suspected hypopituitarism in unwell patient best to give steroids and then sort out diagnosis later

About

• The anterior pituitary releases 6 hormones.
• LH/FSH/GH/TSH/ACTH and Prolactin

Causes

• Pituitary adenoma - may be non-functioning or functioning and producing a hormone e.g. Prolactinoma
• Craniopharyngioma -Tumour in a child
• Infiltration - Sarcoid, Tuberculosis, haemochromatosis
• Vascular - Sheehan's syndrome and the acute form - Pituitary apoplexy
• Meningitis, Encephalitis and syphilis
• Trauma - basal skull fracture
• Congenital - Kallmann's syndrome
• Autoimmune with Pituitary Antibodies
• Anorexia, Starvation
• Radiation damage and chaemotherapy
• Kallmann's syndrome - GnRH deficiency + anosmia
• Pituitary apoplexy - sudden headache and visual loss and acutely hypopituitarism
• Empty Sella syndrome - pituitary looks empty but just placed eccentrically. Normal function.

Clinical

• ACTH - reduced cortisol, preserved mineralocorticoids compared with Addison's disease
• Prolactin - see above. Loss of ability to lactate. Raised prolactin may be seen if the pituitary stalk is compressed and there is loss of dopaminergic inhibition/
• LH, FSH infertility, Decreased sex drive, impotence, amenorrhoea
• GH - reduced growth and height before epiphyses fuse. Loss of sense of well-being and muscle bulk,
• TSH - leads to hypothyroidism
• Pressure can affect posterior pituitary - ADH - Cranial diabetes insipidus

Local effects of an expanding Pituitary structural lesion

• Headaches, Bitemporal hemianopia
• Deficiency of local hormones
• Cranial nerve palsies III,IV and VI

Investigations to Assess Pituitary Function

• Serum Prolactin and TSH and T4 and Serum cortisol at 9 am
• Serum IGF-1 and GH, Serum FSH, LH, Oestrogen, Testosterone
• Fasting blood glucose and Hba1c
• Pituitary MRI

Management: Assess and treat the cause and consider replacement therapy

• If patient unwell and you suspect acute hypopituitary then have a low threshold for IV Hydrocortisone 100 mg V 6h. Start Hydrocortisone orally 15-40 mg per day (give 2/3rds in am is ideal but patients forget so can give it all) Typically Hydrocortisone 15 mg am and 5 mg at 4 pm are given.
• Fludrocortisone and other mineralocorticoids are not usually required in hypopituitarism as there is residual adrenal mineralocorticoid activity independent of the pituitary governed by the renin-angiotensin-aldosterone axis
• Give L-thyroxine at a dose to correct T4 level (not TSH level as is usual)
• LH/FSH - Males - testosterone if no wish for fertility, Gonadotrophins if fertility wished. Testosterone via im or orally, transdermally or implant for males.
• LH/FSH - women - oestrogen-progesterone replacement therapy if no wish for fertility. Gonadotropin therapy if fertility wished. Fertility may require Pulsatile GnRH or HCG and FSH
• Growth hormone is not required in most adult patients. Growth hormones administration may be associated with an increase in malignancy