Endocrine Flashcards
What is acromegaly?
Constellation of signs and symptoms caused by hypersecretion of GH in adults (Excess GH before puberty results in gigantism)
What is the aetiology of acromegaly?
- Most cases are a result of GH-secreting pituitary adenoma - Rarely: Excess GHRH causing somatotroph hyperplasia from hypothalamic ganglioneuroma, bronchial carcinoid or pancreatic tumours
What is the epidemiology of acromegaly?
- Rare - Age at diagnosis: 40-50
What are the presenting symptoms of acromegaly?
- Very gradual progression of symptoms over many years - May complain of rings and shoes becoming tight - Increased sweating, headache, carpal tunnel syndrome - Symptoms of hypopituitarism (hypogonadism, hypothyroidism, hypoadrenalism) Visual disturbances (caused by optic chiasmm compression - Hyperprolactinaemia (irregular periods, reduced libido, impotence)
What are the signs of acromegaly on examination?
- Hands: Enlarged spade-like hands with thick greasy skin. Signs of carpal tunnel syndrome. Premature oesteoarthritis (which also affects other large joints, temporomandibular joint) - Face: Prominent eyebrow ridge (frontal bossing) and cheeks, broad nose bridge, prominent nasolabial folds, thick lips, increased gap between teeth, large tongue, progathism, husky resonant voice (thickening vocal cords) - Visual field loss: Bitemporal superior quadrantanopia progressing to bitemporal hemianopia (caused by pituitary tumour compressing the optic chiasm) - Neck: Multi-nodular goitre - Feet: enlarged
What are the investigations for acromegaly?
- Serum IGF-1: GH stimulates liver IGF-1 secretion - Oral glucose tolerance test: Failure of suppression of GH after 75h oral glucose load (false positive results seen in anorexia nervosa, Wilson’s disease, opiate addiction - Pituitary function tests: 9am cortisol, free T4 and TSH, LH, FSH, testosterone (in men) and prolactin (to test for hypopituitarism - MRI of the brain: to image the pituitary tumour and effect on the optic chiasm
How is acromegaly managed?
- Surgical: Trans-spenoidal hypophysectomy is the only curative treatment - Radiotherapy: Adjunctive treatment to surgery - Medical: If surgery is contra-indicated or reduced - SC somatostatin analogues (octreotide, lanreotide) Side effects: abdo pain, steatorrhoea glucose intolerance, gallstones, irritation at injection site - Oral dopamine agonists (bromocriptine, cabergoline) SE: nausea, vomiting, constipation, postural hypotension (raised dose gradually and take it during meals) psychosis - GH antagonist (pegvisomant) - Monitor: GH and IGF1 levels can be used to monitor disease control. Pituitary function tests, echocardiography, regular colonoscopy and blood glucose
What are the possible complications of acromegaly?
- CVS: cardiomyopathy, hypertension - Respiratory: Obstructive sleep apnoea - GI: colonic polyps - Reproductive: Hyperprolactinaemia - Metabolic: Hypercalcaemia, Hyperphosphataemia, renal stones, diabetes mellitus, Hypertriglyceridaemia - Psychological: Depression, psychosis (resulting from dopamine agonist therapy) - Complications of surgery: Nasoseptal perforation, hypopituitarism, adenoma recurrence, CSF leak, infection (meninges, sphenoid sinus)
What is the prognosis for acromegaly?
Good with early diagnosis and treatment, although physical changes are irreversible
What is adrenal insufficiency?
Deficiency of the adrenal cortical hormones (e.g. mineralocorticoids, glucocorticoids and androgens)
What is the aetiology of adrenal insufficiency?
- Primary (Addison’s disease): Autoimmune - Infections: Tuberculosis, meningococcal septicaemia (Waterhouse-Friderischen syndrome), CMV (HIV patients), histoplasmosis - Infiltration: Metastasis (e.g. lung, breast, melanoma), lymphoma, amyloidosis - Infarction: Secondary to thrombophilia - Inherited: Adrenoleukodystrophy, ACTH receptor mutation - Surgical: After bilateral adrenalectomy - Secondary: Pituitary or hypothalamic disease - Iatrogenic: Sudden cessation of long-term steroid therapy
What is the epidemiology of adrenal insufficiency?
Most common cause is iatrogenic - Primary causes are rare
What are the presenting symptoms of adrenal insufficiency?
- Chronic presentation: Non-specific symptoms such as dizziness, anorexia, weight loss, diarrhoea, vomiting, abdominal pain, lethargy, weakness, depression - Acute presentation (Addisonian crisis): Acute adrenal insufficiency with major haemodynamic collapse often precipitated by stress (e.g. infection or surgery)
What are the signs of adrenal insufficiency on examination?
- Postural hypotension - Increased pigmentation: Generalised but more noticeable on buccal mucosa, scars, skin creases, nail, pressure points (resulting from melanocytes being stimulated by raised ACTH level) - Loss of body hair in women (androgen deficiency) - Associated autoimmune conditions: e.g. vitiligo - Addisonian crisis: Hypotensive shock, tachycardia, pale, cold, clammy, oliguria
What are the investigations for adrenal insufficiency?
- Confirm the diagnosis: 9am serum cortisol less than 100nmol/L is diagnostic of adrenal insufficiency. - Identify the level of defect ACTH: Raised in primary disease, decreased in secondary. Long Synacthen test - Identify the cause: Autoantibodies (against 21-hydroxylase). Abdominal CT or MRI. Other tests e.g. adrenal biopsy for microscopy, culture, PCR, depending on the suspected causes Check TFTs - Investigations in ‘Addisonian crisis’: FBC
How is adrenal insufficiency managed?
- Addisonian crisis: Rapid IV fluid rehydration. 50ml of 50% dextrose to correct hypoglycaemia. IV 200mg hydrocortisone bolus followed by 100mg 6 hourly (until BP stable). Treat the precipitating cause (e.g. antibiotics for infection). Monitor temperature, pulse, respiratory rate, BP, sat 02 and urine output - Chronic: Replacement of glucocorticoids with hydrocortisone (three times/day) and mineralocorticoids with fludrocortisone. Hydrocortisone dosage needs to be increased during acute illness or stress. If associated with hypothyroidism, give hydrocortisone before thyroxine (to avoid precipitating Addisonian crisis) - Advice: Steroid warning card, Medic-alert bracelet, emergency hydrocortisone ampoule, patient education
What are the possible complications of adrenal insufficiency?
Hyperkaelaemia Death during Addisonian crisis
What is the prognosis of adrenal insufficiency?
- Adrenal function rarely recovers, but normal life expectancy can be expected if treated - Type I (autosomal recessive disorder caused by mutation in the AIRE gene which encodes a nuclear transcription factor): Addison’s disease, chronic mucocutaneous candidiasis, hypoparathyroidism - Type II: Addison’s disease, diabetes mellitus Type I, hypothyroidism, hypogonadism
What is carcinoid syndrome?
Constellation of symptoms caused by systemic release of humoral factors (biogenic amines, polypeptides, prostaglandins) from carcinoid tumours
What is the aetiology of carcinoid syndrome?
- Carcinoid tumours are slow growing neuroendocrine tumours mostly derived from serotonin-producing enterochromaffin cells - They produce secretory products such as serotonin, histamine, tachykinins, kallikrein and prostaglandin - May be classified into fore-,mid-, hind-gut tumours, 75-80% tumours include appendix and rectum, where they are often benign and non-secretory - Also found in other parts of large intestine, stomach, thymus, bronchus and other organs - Hormones released into the portal circulation are metabolised in the liver - Thus symptoms typically do not appear until there are hepatic metastases (resulting in the secretion of tumour products into the hepatic veins) or release into the systemic circulation from bronchial or extensive retroperitoneal tumours
What is the epidemiology of carcinoid syndrome?
- Rare - Asymptomatic carcinoid tumours are more common and may be an incidental finding after rectal biopsy or appendectomy - 10% of patients with multiple endocrine neoplasia (MEN) type 1 have carcinoid tumours
What are the presenting symptoms of carcinoid syndrome?
- Paroxysmal flushing - Diarrhoea - Crampy abdominal pain - Wheeze - Sweating - Palpitations
What are the signs of carcinoid syndrome on examination?
- Facial flushing, telangiectasia, wheeze - Right sided heart murmurs: tricuspid stenosis, regurgitation or pulmonary stenosis - Nodular hepatomegaly in cases of metastatic disease - Carcinoid crisis: Profound flushing, bronchospasm, tachycardia and fluctuating blood pressure
What are the investigations for carcinoid syndrome?
- 24h urine collection: 5-HIAA levels (a metabolite of serotonin, false positive with high intake of certain fruit/drugs e.g. bananas and avocados, caffeine, paracetamol - Blood: Plasma chromogranin A & B, fasting gut hormones - CT or MRI scan: To localises the tumour - Radioisotope scan: Radiolabelled somatostatin analogue (e.g. indum-111 octreotide) helps localise tumour - Investigations for MEN-1
What is diabetes insipidus?
A disorder of inadequate secretion of a or insensitivity to vasopressin (ADH) leading to hypotonic polyuria
What is the aetiology of diabetes insipidus?
- Failure of ADH secretion by the posterior pituitary (central/cranial) or insensitivity of the collecting duct to ADH (nephrogenic) - Water channels (aquaporins) fails to activate and the luminal membrane of the collecting duct remained impermeable to water - This results in large volume hypotonic urine and polydypsia
What causes central diabetes insipidus?
- Idiopathic - Tumours e.g. pituitary tumours - Infiltrative e.g. sarcoidosis - Infection e.g. meningitis - Vascular e.g. aneurysms, Sheehan syndrome - Trauma (e.g. head injury, neurosurgery, DIDMOAD
What causes nephrogenic diabetes insipidus?
- Idiopathic - Drugs e.g. lithium - Post-obstructive uropathy - Pyelonephritis - Pregnancy - Osmotic diuresis (e.g. diabetes mellitus)
What is the epidemiology of diabetes insipidus?
- Depends on aetiology, but median age of onset is 24 yrs
What are the presenting symptoms of diabetes insipidus?
- Polyuria, nocturia and polydipsia (excessive thirst) - Enuresis and sleep disturbances in children - Other symptoms depend on the aetiology
What are the signs of diabetes insipidus on examination?
- Cranial diabetes insipidus has few signs if patients drink adequate fluids - Urine output is often more than 3L/24h - If fluid intake is less than fluid output, signs of dehydration may be present (e.g. tachycardia, reduced tissue turgor, postural hypotension, dry mucous membranes) - Signs of the cause (e.g. visual field defect)
What are the investigations for diabetes insipidus
- Blood: U&E and Ca++ (Na+ may be rise secondary to dehydration) Raised plasma osmolality. Decreased urine osmolality - Water deprivation test: Water is restricted for 8h. Plasma and urine osmolality are measured every hour over the 8h. Weigh the patient hourly to monitor the level of dehydration; stop the test if the fall in body weight more than 3%. Desmopressin is given after 8h and urine osmolality is measured
How is diabetes insipidus managed?
- Treat the identified cause if possible - Cranial diabetes insipidus: Desmopressin (DDAVP), a vasopressin analogue, can be given to potentiate effects of residual vasopressin - Nephorogenic diabetes insipidus: Sodium and/or protein restriction may help polyuria. Thiazine diuretics
What are the complications of diabetes insipidus?
- Hypernatraemicd dehydration - Excess desmopressin therapy may cause hyponatraemia
What is the prognosis of diabetes insipidus?
- Variable depending on cause - Cranial diabetes insipidus may be transient following head trauma - Cure of cranial or nephrogenic insipidus may be possible on removal of cause e.g. tumour resection, drug discontinuation
What is type 1 diabetes mellitus?
Metabolic hyperglycaemic condition caused by absolute insufficiency of pancreatic insulin production
What is the aetiology of type diabetes mellitus?
- Caused by destruction of the pancreatic insulin producing B cells, resulting in absolute insulin deficiency. The B cell destruction is caused by an autoimmune process in 90% of patients - Likely to occur in genetically susceptible subjects and is probably triggered by environmental agents. Polymorphisms of a number of genes may influence the risk of type 1 diabetes. These include the gene encoding preproinsulin and a number of genes related to immune system function - Pancreatic B cell autoantigens may play a role in the initiation or progression of autoimmune islet injury. These include gluatmic acid decarboxylase (GAD) insulin, insulinoma associated protein 2 and cation efflux zinc transporter (ZnT8)
What is the epidemiology of type 1 diabetes mellitus?
- On of the most common chronic diseases in childhood with a prevalence of 0.25% in UK - Considerable geographic variation in incidence
What are the presenting symptoms of type 1 diabetes mellitus?
- Often of juvenile onset (under 30yrs). Polyuria/nocturia (osmotic diureses caused by glycosuria), polydipsia (thirst), tiredness, weight loss. Symptoms of complications. Diabetes ketoacidosis: Nausea, vomiting, abdominal pain, polyuria, polydipsia, drowsiness, confusion, coma, Kussmaul breathing (deep and rapid) ketotic breath, signs of dehydration (e.g. dry mucous membranes & reduced tissue turgor) - Signs of complications: examination of feed, test for neuropathy - Signs of associated autoimmune conditions e.g. vitiligo, Addison’s disease, autoimmune thyroid disease
What are the investigations for type 1 diabetes mellitus?
Blood glucose: Fasting blood glucose over 7mmol/L or random blood glucose over 11 mmol. 2 pos results needed before diagnosis HbA1C: Estimates overall blood glucose levels in past 2-3 months FBC: MCV, reticulolytes ( raised erythrocyte turnover causes misleading HbA1c levels) U&E: Monitor for nephropathy and hyperkalaemia caused by ACE inhibitors Lipid profile Urine albumin creatinine ratio CXR: exclude infection ECG: Look for ischaemic changes
How is type 1 diabetes mellitus managed?
Diabetes keoacidosis consider HDU/ICU input, central line, arterial line and urinary catheter if severe acidosis, hypotensive or oliguric - Insulin - Fluids - Potassium replacement - Monitor blood glucose - Broad spectrum antibiotics if infection suspected - NBM for at least 6h (gastroparesis is common) - NG tube: If GCS is reduced to prevent vomiting and aspiration - Refer to diabetes team for patients education
What does glycaemic control involve in type 1 diabetes mellitus?
- Advice and patient education: Diabetes nurse specialist dietitians. SC insulin: Short acting insulin (e.g. Lispro, aspart, glusine) three times daily before each meal and one long-acting insulin. Injection sites should be rotated - Insulin pumps slightly better glycaemic control but are costly and cumbersome for some patients and ketoacidosis may occur if pump malfunction - Monitor: control of symptoms, regular finger prick tests by patient, monitoring HbA1c levels - Screening and management of complications Treatment of hypoglycaemia
What are the possible complications of type 1 diabetes mellitus?
- Diabetic ketoacidosis: reduced insulin and increased counter-regulatory hormones result in raised hepatic gluconeogenesis and decreased peipheral glucose utilisation. - Microvascular: Retinopathy, nephropathy, neuropathy - Macrovascular: Peripheral vascular disease, ischaemic heart disease, stroke (TIA) - Complications of insulin treatment: Weight gain, fat hypertrophy at insulin injection sites - Hypoglycaemia caused by missed a meal r overdosage of insuline
What is the prognosis of type 1 diabetes mellitus?
Depends on early diagnosis, good glycaemic control and compliance with screening and treatment - Vascular disease and renal failure are major causes of increased morbidity and mortality
What is type 2 diabetes mellitus?
Characterised by increased peripheral resistance to insulin action, impaired insulin secretion and increased hepatic glucose output
What is the aetiology of type 2 diabetes mellitus?
- Multi-factoiral ( fenetic and environmental - Obesity: raised plasma free fatty acid levels and adipokines secreted by adipocytes (e.g. leptin, adinonectin, TNF-a, resistin) contribute to peripheral insulin resistance. Chronic hyperglycaemia can have a toxic effect on B cells - Secondary diabetes: Pancreatic diseases (chronic pancreatitis, hereditary haemochromatosis, pancreatic cancer, surgical removal of pancreas), Endocrinopathies (Cushings), Drugs (eg. corticosteroids
What is the epidemiology of type 2 diabetes mellitus?
People of Asian, African and Hispanic descent are at greater risk. Incidence has increased over last 20 years, in parallel with increased obesity worldwise
What are the presenting symptoms of type 2 diabetes mellitus?
- May be incidental finding - Polyuria, polydipsia, tiredness. Patients may present with hyperosmolar hyperglycaemic state (also known as hyperosmolar, non ketotic state). Infections - Assess for other cardiovascular risk factors: hypertension, hyperlipidaemia and smoking
What are the signs of type 2 diabetes mellitus on examination?
- Measure weight and height, weight circumference, blood pressure - Look for signs of complications - Diabetic foot: both ischaemic and neuropathic signs. Dry skin, reduced subcutaneous tissue, corns and calluses, ulceration, gangrene - Charcot’s arthropathy and signs of peripheral neuropathy, foot pulses are decreased in ischaemic foot - Skin changes: aNecrobiosis lipoidica diabeticorum (well-dermacated plaques on the shins or arm with shiny atrophic surface and red-brown edges), granuloma annulare (flesh coloured paplules coalescing in rings on the back of hands and fingers), diabetic dermopathy (depressed pigmented scars on shins)
What are the investigations for type 2 diabetes mellitus?
Diagnosed if one or more of the following are present - Symptoms of diabetes and random plasma glucose over 11.1mmol/L - Fasting plasma glucose over 7mmol - Two hour plasma glucose over 11.mmol after a 75g oral glucose tolerance test Monitor: HbA1c, U&Es, lipid profile, estimated glomerular filtration rate using MDRD calculator - Spot urine albumin. Creatinine ratio (to detect microalbuminaria)
How is type 2 diabetes mellitus managed?
- Glycaemic control - Sulphonylureas (gliclazide) block ATP-sensitive K channels in B cells, stimulating insulin release. Metformin inhibits hepatic gluconeogenesis. Plioglitazone activate PPAR gamma & reduced peipheral insulin resistance - Retinopathy: Regular digital retinal photography, ophthomology referral and laser photo-coagulation if necessary - Nephropathy: Monitor U&Es and estimated GFR using MDRD calculator, spot urine analysis - Neuropathy: Regular examination and inspection of the feet for ulcers, 10g monofilament testing, joint vibration, foot hygeine, amitriptuline - Vascular disease: Regular examination of foot pulses - Diabetic foot: Educate to examine foot regularly. Diabetic footwear. Podiatry assessment. For infections, clean and dress regularly, swan for culture and sensitivity - Screen for and test cardiovascular risks: Lose weight, exercise, stop smoking, BP control, all diabetics patients should be started on a statin. Aspirin in patients with diabetes and additional cardiovascular risk factor
What does glycaemic control in type 2 diabetes mellitus involve?
- At diagnosis: Lifestyle & metformin - If HbA1c more than 7% after 3 months: Lifestyle & metformin & sulphonurea - If HbA1c more than 7% after 3 months: Lifestyle & metformin % basal insulin - If HbA1c more than 7% and fasting blood glucose less than 7mmol/L: Add premeal rapid acting insulin - Sulphonurea may be given as monotherapy in patients who cannot tolerate metformin
What advice and patient education should be given to type 2 diabetics?
INFORM PT - Information: Diabetic nurses, leaflets, websites etc, explaining diabetes control, complications - Nutrition: Optimizing meal plans, diet - Foot care: Regular inspection, appropriate footwear, role of chiropodist - Organisations: Local and national support groups - Recognition and treatment of hypoglycaemia - Monitoring capillary blood glucose and charting it. Monitoring for ketones during intercurrent illness - Pregnancy: Strict glycaemic control and planning of conception - Treatment: Action, duration and administration, technique for insulin, change the site of injection, explain the need to plan exercise
What are the possible complications of type 2 diabetes mellitus?
- Hyperosmolar hyperglycaemic state: Due to insulin deficiency as diabeteic ketoacidosis but patient is usually old and may be presenting for the first time, history is longer (e.g. 1 week). Distal symmetrical sensory neuropathy, painful neuropathy, carpal tunnel syndrome, diabetic amyotrophy, mononeuritis, autonomic neuropathy, gastroparesis, impotence, urinary retention. Nephropathy: Microambinuria, proteinuria and eventually renal failure. - Retinopathy: Backgroun: dot and blot haemorrhages, hard exudates. Pre-proliferative: Cotton wool spots, venous beading. Proliferative: New vessels on the disc and elsewhere. Maculopathy: Macular oedema, exudates within 1 disc diameter of the centre of the fovea, haemorrhage within 1 disc diameter of centre of the fovea associated with reduced visual acuity. Also prone to glaucoma, cataracts, transient visual loss - Macrovascular: ischaemic heart disease, stroke, pvd
What is the prognosis of type 2 diabetes mellitus?
- Intensive therapy to achieve lower levels of glycaemia, lowers the risk of development and progression of diabetic microvascular complications
What is Grave’s disease?
Autoimmune thyroid condition associated with hyperthyroidism
What is the aetiology of Grave’s disease?
- Autoimmune - Stimulation of thyroid by TSH receptor antibodies causing thyroid hormone overproduction - Genetic (80%) and environmental (20%) factors
What is the epidemiology of Grave’s disease?
- Most common form of hyperthyroidism in most areas of world
What are the presenting symptoms of Grave’s disease?
- Heat intolerance - Sweating - Weight loss - Palpitations - Tremor - Irritability
What are the signs of Grave’s disease on examination?
- Wide pulse pressure - Diffuse goitre - Tachycardia - Orbitopathy - Scalp hair loss - Moist, velvety skin - Cardiac flow murmir - Thyroid bruit - Oncholysis - Vitiligo - Pretibial myoedema - Acropachy
What are the investigations for Grave’s disease?
- TSH: suppressed - Serum free T4: Elevated, except in T3 toxicosis or subclinical disease - Serum free or total T2: elevated, except in subclinical disease
What is female hypogonadism?
Characterised by impairment of ovarian function
What is the aetiology of female hypogonadism?
Primary hypogonadism (hypergonadotrophic) - Gonadal dysgenesis: Chromosomal abnormalities (e.g. Turner’s syndrome), FMR1 gene pre-mutation carriers (CGG repeats between 55&200) - Gonadal damage: Autoimmune, iatrogenic (chemotherapy, radiation, surgery) - Secondary hypogonadism (hypogonadotrophic) - Functional: Stress, weight loss, excessive exercise, eating disorders (anorexia nervosa, bulimia) - Pituitary/hypothalamic tumours and infiltrative lesions: Pituitary adenomas, craniopharyngiomas, haemochromatosis - Hyperprolactinaemia: Prolactinomas or tumours causing pituitary stalk compression - Congenital GnRH deficiency: Kallmann’s syndrome, idiopathic
What is the epidemiology of female hypogonadism?
Symptoms of oestrogen deficiency - Night sweats, hot flush, vaginal dryness and dyspareunia - Reduced libido, infertility - Symptoms of underlying cause
What are the signs of female hypogonadism on examination?
Pre-pubertal hypogonadism: - Delayed puberty (primary amenorrhoea, absent breast development, no secondary sexual characteristics) - Eunuchoid proportions (e.g. long legs, increased arm span for height) Post-pubertal hypogonadism: - Regression of secondary sexual characteristics (loss of secondary sexual hair, breast atrophy). Perioral and periorbital fine facial wrinkles - Signs of underlying cause/ associated symptoms - Hypothalamic/pituitary disease: Visual field defects - Kallmann’s syndrome: Anosmia - Turner’s syndrome: Short stature, low posterior hairline, high arches palate, widely spaced nipples, wide carrying angle, short fourth and fifth metacarpals, congenital lymphoedema - Patient’s with autoimmune primary ovarian failure: Signs of autoimmune disease e.g. hyperpigmentation in Addison’s disease or vitiligo
What are the investigations for female hypogonadism?
- Reduced serum oestradiol. Serum FSH & LH: Raised in primary (due to decreased feedback inhibition by ovarian oestradiol and inhibin). Reduced or inappropriately normal FSH/LH in secondary hypogonadism - Investigation to determine the aetiology - Primary: Karyotype (to look for chromosomal abnormalities: complete or partial deletion of the X chromosome in Turner’s syndrome or presence of Y chromsome. Pelvic imagine: in pts with primary amenorrhoea, to demonstrate presence or absence of uterus and vagina and vaginal or cervical outlet obstruction (Mullerian agenesis, androgen insensitivity, transverse vaginal septum, imperforate hymen - In unexplained pre-mature ovarian failure: screening for pre-mutation in FMR1 gene after appropriate genetic counselling and informed consent - Secondary: Pituitary function tests (9am cortisol, TFTs, prolactin), visual field testing, hypothalamic-pituitary MRI, smell tests for anosmia. Serum transferrin saturation if hereditary haemochromatosis is suspected - Turner’s: Periodic echo and cardio follow-up. Renal USS - Autoimmune oophoritis: Evaluate for autoimmune adrenal insufficiency
What is male hypogonadism?
A syndrome of reduced testosterone production, sperm production or both
What is the aetiology of primary male hypogonadism?
- Gonadal dysgensis: Klinefelter’s syndrome (XXY), undescended testes (cryptochidism) - Gonadal damage: Infection (e.g. mumps), torsion, trauma, autoimmune, iatrogenic (chemotherapy, surgery, radiation) - Rare causes: Defects in enzymes involved in testosterone synthesis, myotonic dystrophy
What is the aetiology of secondary male hypogonadism?
- Pituitary/hypothalamic lesions - GnRH deficiency: Kallmann’s syndrome (associated with anosmia), idiopathic - Hyperprolactinaemia - Systemic/chronic diseases - Rare causes: Genetic mutation. Secondary hypogonadism may be seen in a number of are syndromes - Prader-Willi syndrome: Loss of critical region on chromosome 15 causing obesity and short stature, small hands, almond-shaped eyes, learning difficulty/postnatal hypotonia - Laurence-Moon-Biedl syndrome: Obesity, polydactyly, retinitis pigmentosa, learning difficulty
What is the epidemiology of male hypogonadism?
- Primary accounts for 30-40% of male infertility, secondary accounts for 1-2% - Most common cause of primary hypogonadism is Klinefelter’s syndrome
What are the presenting symptoms of male hypogonadism?
- Delayed puberty ( f the onset is before puberty) - Reduced libido, impotence, infertility - Symptoms of underlying cause e.g. Klinefelter’s syndrome: intellectual dysfunction and behavioural abnormalities which cause difficulty in social interactins
What are the signs of male hypogonadism on examination?
- Measure testicular volume using Prader’s orchidometer (ellipsoids of different sizes) Normal adult testicular volume: 15-25 ml Pre-pubertal hypogonadism: - Signs of delayed puberty (high pitched voice, reduced pubic/axillary/facial hair, small or undescended testes, small phallus), gynaecomastia, eunuchoid proportions, arm span more than height, lower segment larger than upper segment ( delayed fusion of epiphyses and continued growth of bones) - Features of underlying cause e.g. cryptochidism, anosmia in Kallmann’s Postpubertal hypogonadism: - Reduced pubic/axillar/facial hair, soft and small tests, gynaecomastia, fine perioral wrinkles. Features of the underlying cause e.g. visual field defects due to pituitary tumour, signs of systemic chronic illness