Endocrinology Notes

Endocrinology

Pituitary Tumours

Endocrine vs local effects

Local effects: CNS + visual fields (optic chiasm compressionbitemporal hemianopia)+ headache

Prolactinoma

Most common pituitary tumour. Usually a microadenoma i.e. <1cm. Most are sporadic; also MEN1. Of lactotroph cells. P

PC: oligo/amenorrhea, galactorrhoea, decreased libido and fertility, erectile dysfunction

Ix: prolactin serum level. MRI pituitary

Mx: Mainstay is medical. Ergot dopamine agonists e.g. cabergoline (need an echocardiogram with this as it leads to valve disease)

Differential Dx: metaclopramide, domperidone, haloperidol, pregnancy/lactation, hypothyroidism, PCOS, CRF

Non-functioning pituitary adenoma

Second commonest pituitary tumour

PC: mass effects and/or hypopituitarism; rarely, pituitary apoplexy (bleed into pituitary gland, differential diagnosis of SAH)

Mx: monitor with annual MRI. Replace hormones. Transphenoidal pituitary resection, radiotherapy.

Hypopituitarism

PC: Weight loss/gain; lethargy; hypotension; oligo/amenorrhoea; decreased libido and fertility; thirst, polyuria, polydipsia

Biochem: Often done in 1 blood test:

• IGF1

• Prolactin

• LF, FSH

• TSH, T4, T3

• 9am testosterone/oestradiol

• 9am cortisol

• Urine and plasma osmolalities

• U & Es (hyponatraemia in SIADH)

Mx: Replace hormones in this order: Hydrocortisone; levothyroxine; sex hormones; GH replacement. If there is posterior hypopituitarism, treat diabetes insipidus with desmopressin.

Acromegaly

Anterior pituitary somatotroph cells, majority spontaneous, macroadenomas, in MEN1 or FIPA syndromes.

PC:

• Musculoskeletal: increased interdental space, frontal bossing, prognathism, carpal tunnel syndrome, osteoarthritis, soft tissue swelling, macroglossia

• Respiratory: sleep apnoea

• Metabolic: diabetes mellitus/impaired glucose tolerance

• Cardio: hypertension, LVH

• Nervous: pituitary tumour effects, carpal tunnel syndrome, diabetic polyneuropathy, nerve compression elsewhere e.g. facial nerve through temporal petrous bone

• Gastrointestinal: colonic polypsmalignancy

Dx: random IGF1 level high. Random GH levels are not useful. Oral glucose tolerance test shows no suppression of GH.

Mx: transphenoidal pituitary resection. If large, give somatostatin analogue or radiotherapy.

Cushing’s Syndrome

Microadenoma of corticotroph cells of anterior pituitary true Cushing’s Disease

PC:

• Skin: acne, hirsutism, striae, thin skinbruising

• Metabolic: centripetal obesity, interscapular and supraclavicular fat pads, ‘buffalo hump’, ‘moon face’, impaired glucose tolerance

• Cardio: hypertension

• Musculoskeletal: proximal myopathy, osteoporosis

Dx: May not see microadenoma on MRI pituitary. No suppression of cortisol on low dose dexamethasone test. Then do a high dose dexamethasone test to if CRH is inappropriately high too (for hypothalamic CRH production). Can do inferior petrosal sinus sampling to lateralise the tumour prior to surgery.

Mx: Surgery. Fails: more surgery. Bilateral adrenalectomy if severe (Nelson’s Syndrome: accelerated growth of ACTH-cells due to no negative feedback from circulating cortisol)

Adrenal Cushing’s

An adrenal adenoma or carcinoma produces corticosteroid. ACTH is low.

Dx: Failure to suppress on low dose dexamethasone and ACTH is low.

Mx: Adrenalectomy and medical cortisol-producing blockers.

Risks: Increased risk of PE, DVT, and overwhelming infection.

PCOS

To diagnose, need two out of three of: oligo/amenorrhoea; hyperandrogenism; polycystic ovaries on USS. Exclude Cushing’s, CAH, pituitary adenoma, testosterone-producing tumours.

Mx: lose weight, metformin, Dianette, androgen receptor blocker (spironolactone) or androgen production blocker (finasteride).

Hypercalcaemia

Causes:

• Primary hyperparathyroidism

• Malignancy: myeloma, bone metastases

• Vitamin D intoxication

• Familial hypocalciuric hypercalcaemia (urinary calcium is inappropriately low, thus causing the hypercalcaemia; in contrast, in primary hyperparathyroidism the urine calcium will be appropriately high)

• Drugs: thiazides, Lithium, hyperthyroidism

• Immobilisation

• Tertiary hyperparathyroidism

• Addison’s Disease

Primary hyperparathyroidism

Usually a solitary parathyroid adenoma. Sometimes parathyroid hyperplasia. Very rarely, a parathyroid cancer (in MEN1/2).

Biochem: Increased PTH, increased plasma calcium, increased urinary calcium

Ix: USS neck. Sestamibi scan. DEXA for osteoporosis. Exclude myeloma and bone metastases. Renal USS (?tertiary hyperparathyroidism)

Mx: surgery if symptomatic, or if asymptomatic with bad biochemistry, or if symptomatic with osteoporosis

Hyperthyroidism

Causes:

• Graves’ disease

• MNG

• Toxic adenoma

• Exogenous iodine or thyroxine (weight loss, iatrogenic)

• Early phase thyroiditis esp. Hashimoto’s

• Amiodarone (can also cause hypothyroidism)

• Lithium

• TSHoma of the pituitary (rare)

• Thyroid storm

• Choriocarcinomaincreased betahCG

Symptoms & Signs of all types of hyperthyroidism:

• Irritability, anxiety

• Psychosis

• Fatigue,...

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