#7553 - Endocrinology - Medical Finals & OSCEs 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, weakness

• Tremor

• Tachycardia and atrial fibrillation

• Sweating and heat intolerance

• Diarrhoea with or without steatorrhoea

• Weight loss despite increased appetite OR increased appetite leads to weight gain

• Urticaria/pruritis

• Proximal myopathy

• Gynaecomastia

• Oligo/amenorrhoea

• Decreased libido

• Dilated pupils

• Ophthalmoplegia

• Lid lag

• Conjunctival suffusion or irritation

• Brisk reflexes

• Palmar erythema

• Goitre

Symptoms & Signs unique to Graves’ disease:

• Exophthalamos

• Acropachy

• Pretibial myxoedema

• Onycholysis

• Signs of vitiligo, pernicious anaemia, Addison’s, T1DM

Graves’ Disease

Anti-TSH-receptor antibodies. A diffuse symmetrical goitre with a bruit. Acropachy and eye disease are unique. Associated with other autoimmune conditions esp. vitiligo, Addison’s, T1DM and pernicious anaemia. Young women.

Ix: TFTs. TSH-receptor antibodies. Thyroid uptake scan (scintogram) if antibody negative.

Mx: Carbimazole (drug rash, arthropathy, *agranulocytosisneutropaenic sepsis*. Propylthiouracil if pregnant. Beta-blockers (propanolol gives AF and tachycardia control but also decreases T4). If CHADS-VASc highanticoagulate if in AF. *Avoid amiodarone*. Grave’s often burns out after ~1yr so monitor. If they have relapsed (more likely in smokers) then can occur total thyroidectomy with levothyroxine for life.

Multinodular goitre

Second most common cause of hyperthyroidism. The goitre is large, irregular and nodular, one lobe usually predominates. This may not produce T4. Rarely, it can have malignant transformation.

PC: hyperthyroidism. Dysphagia, orthopnoea, SOB. Pemberton’s sign (cruel to do).

Ix: TFTs, Ct (?retrosternal extension). thyroid scintogram shows patchy uptake or a hotspot.

Mx: Radioactive iodine-131. Tracheal compressionthyroidectomy. Thyroidectomy in younger patients are there is a risk of thyroid cyst haemorrhage, acute tracheal haemorrhage, toxic/malignant change, and also for cosmesis.

Toxic thyroid adenoma

Benign follicular adenoma, 10% are ‘hot’ (produce T4). All solitary nodules need an FNA. Cytology cannot reliably distinguish from carcinomas, so remove them. A thyroid scintogram would show ‘cold spots’. After thyroid surgery, thyroglobulin (a marker of thyroid tissue) should be low; if it rises, there is cancer/thyroid regrowth.

Thyroid Storm

T4 is released during surgery leading to a thyrotoxicosis crisis with a 10% mortality. It can also be triggered be stress/infection/ablation.

PC: Rapid deterioration with tachycardia,...