Endocrinology III Flashcards
Causes of impotence A Addison's disease B Drug induced C Haemochromatosis D Klinefelter's syndrome E Non-functioning pituitary tumour F Primary gonadal failure G Prolactinoma H Psychological I Thyrotoxicosis J Vascular
Select the most likely diagnosis for the following patients presenting with impotence. Normal ranges: Testosterone 10-30 nmol/L LH 1-10 mu/L FSH 1-10 mu/L Prolactin 100-500 mu/L A 62-year-old male presents concerned regarding impotence. His wife of 30 years died three years ago and he found a partner six months ago but has been unable to have intercourse due to erectile dysfunction. He is treated for agitated depression and has been prescribed risperidone. His results show:
Testosterone 8.8 nmol/l
LH 2.1 mu/l
FSH 3 mu/l
Prolactin 850 mu/l
Drug induced
There are numerous causes of drug induced impotence. In this case, risperidone, a dopaminergic antagonist, is associated with hyperprolactinaemia and can produce hypogonadotrophic hypogonadism as a consequence.
Causes of impotence A Addison's disease B Drug induced C Haemochromatosis D Klinefelter's syndrome E Non-functioning pituitary tumour F Primary gonadal failure G Prolactinoma H Psychological I Thyrotoxicosis J Vascular Select the most likely diagnosis for the following patients presenting with impotence. Normal ranges: Testosterone 10-30 nmol/L LH 1-10 mu/L FSH 1-10 mu/L Prolactin 100-500 mu/L
An 18-year-old male presents with concerns over impotence and reduced libido. He has recently entered into his first relationship with a woman and is concerned by his poor penile development, unaware of any erections and little sex drive. On inspection you note that he is tall and has little facial hair. Results show: Testosterone 7 nmol/l LH 22 mu/l FSH 33 mu/l Prolactin 255 mu/l
Klinefelter’s syndrome is associated with XXY karyotype and is associated with elevated LH/FSH and low testosterone.
Although associated with primary gonadal failure it is important to recognise Klinefelter’s as causing the former and the features include:
the poor pubertal development
lack of shaving
tall stature
often poor school performance (Klinefelter’s is associated with lower IQ).
Treatment is with testosterone replacement.
It is highly likely that he will be infertile.
Endocrine disorders A ACTH producing tumour B Hyperaldosteronism C MEN 1 D MEN 2a E MEN 2b The following patients have all presented with endocrine disorders. Please choose the most appropriate answers from the given list. Hyperprolactinaemia and gastric ulcers
MEN 1
The multiple endocrine neoplasia syndromes are characterised by tumours involving two or more endocrine glands. Their inheritance is autosomal-dominant or sporadic.
MEN 1 is characterised by anterior pituitary adenoma, pancreatic tumours (gastrinomas, insulinomas) and parathyroid hyperplasia.
Endocrine disorders A ACTH producing tumour B Hyperaldosteronism C MEN 1 D MEN 2a E MEN 2b The following patients have all presented with endocrine disorders. Please choose the most appropriate answers from the given list.
Hypertension, neck lump and tachycardia
MEN 2a
Multiple endocrine neoplasia 2 describes the association of medullary thyroid carcinoma, phaeochromocytomas and thyroid tumours.
MEN 2 is subdivided into 2a, 2b and medullary thyroid carcinoma only:
MEN 2a is the most common variant with parathyroid disease commonly following the development of medullary thyroid cancer, 50% of patients develop phaeochromocytomas.
MEN 2b is characterised by medullary thyroid carcinoma, parathyroid hyperplasia, phaeochromocytoma, marfanoid features and mucosal neuromas. In MEN 2b, the medullary cancer is very aggressive with most patients dying before developing either a phaeochromocytoma or hyperparathyroidism.
Endocrine disorders A ACTH producing tumour B Hyperaldosteronism C MEN 1 D MEN 2a E MEN 2b The following patients have all presented with endocrine disorders. Please choose the most appropriate answers from the given list.
Hypokalaemia and alkalosis
Primary hyperaldosteronism results from excessive secretion of aldosterone by an adenoma of the adrenal cortex. Aldosterone causes retention of sodium in exchange for potassium and hydrogen in the distal nephron, resulting in hypokalaemic alkalosis and hypertension due to intravascular fluid expansion secondary to sodium retention.
Patients may also report
Muscle weakness
Cramps
Polydipsia
Polyuria.
Homeostatis: Hormones involved in homeostatic control
A ACTH
B CRH
C Dopamine
D FSH
E GnRH
F Growth hormone
G LH
H Prolactin
I Somatostatin
J TSH
From the options, please select the correct hormone for each of the descriptions below.
You may use each option once, more than once, or not at all.
This hormone acts on cartilage and liver to release IGF-1.
This hormone promotes iodination of tyrosine residues.
This hypothalamic hormone inhibits the secretion of growth hormone.
In males, this hormone facilitates the generation of spermatozoa.
This hormone inhibits galactorrhoea.
Growth hormone acts on the liver to release IGF-1. IGF-1 then acts on cells around the body, especially cells in the growth plates of the long bones to grow and divide.
TSH acts on the thyroid gland to iodinate tyrosine residues, to produce thyroxine.
This hypothalamic hormone inhibits the secretion of growth hormone.
Somatostatin
Somatostatin has an important role by inhibiting the secretion of growth hormone.
In males, FSH causes generation of spermatozoa, where LH causes the secretion of testosterone from the testes.
This hormone inhibits galactorrhoea.
Dopamine
Dopamine inhibits galactorrhoea, and hence can be used as a treatment.
Which of the following is true of adrenocorticotropic hormone (ACTH)?
(Please select 1 option)
Is increased in the maternal plasma in pregnancy
Is not present in the placenta
Production is governed by the pituitary
Production is maximal about midnight
Secretion is inhibited by mineralocorticoids
Is increased in the maternal plasma in pregnancy
The production of ACTH is governed through the secretion of corticotropin-releasing hormone from the hypothalamic nuclei.
It governs cortisol secretion where cortisol is secreted maximally in the morning and concentrations are at a nadir at midnight.
ACTH can be expressed in numerous tissues besides the pituitary and including the placenta.
ACTH concentrations rise in stress, disease and in pregnancy.
Through negative feedback, glucocorticoids (not mineralocorticoids - aldosterone) switch off ACTH production.
n which of the following circumstances does the release of catecholamines from the adrenal medulla increase?
(Please select 1 option)
Approximately one hour following a myocardial infarction
During sleep in healthy individuals
Following an increase in blood sugar
In acute haemorrhage once hypertension develops
When the nerves to the adrenal gland are stimulated
Catecholamine release is generated by:
Stress (i.e. waking)
Sympathetic stimulation (flight, fright, fight response)
During hypoglycaemia (as response to stressful stimuli and counteraction of catecholamines in recruiting glucose)
During illness (e.g. MI, sepsis), and
Hypotensive episodes.
Which of the following is true of the anterior pituitary gland?
Exhibits a constant hormone secretion activity Is connected to the thalamus by neural tissue Is contained in the anterior cranial fossa Produces glycoproteins Produces hormones which share a common beta sub-unit
Glycoproteins
The pituitary stalk connects the anterior pituitary to the hypothalamus and it is contained in the pituitary sella with the optic chiasm and hypothalamus as superior relations.
Glycoproteins such as thyroid-stimulating hormone (TSH) and luteinising hormone (LH) follicle-stimulating hormone (FSH) are produced by the anterior pituitary. These share a common alpha subunit with unique beta subunits.
There is diurnal variation in the secretion of many hormones such as LH, adrenocorticotropic hormone (ACTH) and growth hormone (GH).
Which of the following is true regarding thyroid hormones?
(Please select 1 option)
D-thyroxine is more active than L-thyroxine
Starvation causes plasma T3 to rise
T4 acts more rapidly than T3
Thyroid binding globulin (TBG) is increased in pregnancy
Triiodothyronine (T3) is converted in the tissues to thyroxine (T4)
T3 is the major active thyroid hormone but the majority is produced via peripheral de-iodination of T4.
Thyroid binding globulin (TBG) is increased in pregnancy
Most binding proteins, including TBG, are increased in pregnancy and therefore it is much more important to measure free thyroid hormone concentrations than total.
Illness and starvation produce a decline in both T4 and T3 concentrations.
The isomer D-T4 is inactive, it is L-T4 that is the active molecule.
Which of the following is untrue of the thyroid gland?
(Please select 1 option)
Actively traps inorganic iodine from plasma
Enlarges during normal pregnancy
Functions from the twelfth week of fetal development
Is stimulated by posterior pituitary hormones
Stores colloid outside epithelial cells
Is stimulated by posterior pituitary hormones
Thyroid hormone production is stimulated by the anterior pituitary hormone (thyroid stimulating hormone [TSH]), and secretion begins from approximately the twelfth week of gestation. The foetus remains dependent on maternal thyroid hormones until about 20 weeks.
Triiodothyronine (T3) and thyroxine (T4) are manufactured within the thyroid cells through iodination of tyrosine. The synthesised T3 and T4 are then stored within the colloid at the centre of the thyroid follicles.
In the mother the thyroid, like most other endocrine organs, moderately enlarges during pregnancy.
Which of the following is correct regarding the adrenal glands?
(Please select 1 option)
Cortices contain chromaffin cells
Lie posteriorly to the diaphragm
Lymphatic drainage is to the superficial inguinal nodes
Medulla is derived from mesoderm
On the left lies behind the pancreas
On the left lies behind the pancreas
They are contained within the same membrane as the kidney but separated from them by a fibrous layer of tissue.
The right gland is tetrahedral in shape and lies lower than the left, which is semilunar in shape and usually the larger of the two. Each gland weighs approximately 5 grams and measures approximately 50 mm vertically, 30 mm across and 10 mm thick.
The right lies between the diaphragm posteriorly and the IVC anteromedially. Superiorly lies the bare area of the liver. Its inferior end is covered by peritoneum reflected over it from the liver.
The left lies in the stomach bed, with anterior relations of the stomach and pancreas and posteriorly with the diaphragm. Its inferior part is not covered by peritoneum as it is crossed anteriorly by the tail of the pancreas and splenic vessels.
The adrenal medulla contains the chromaffin cells.
Embryologically the medulla is derived from neural crest cells and cortex from mesoderm.
Which of the following is correct of prolactin (PRL)-secreting pituitary tumours?
(Please select 1 option)
Are usually macroadenomas at presentation
Produce homonymous hemianopia with a suprasellar extension
Regress during pregnancy
Suprasellar extension is an indication for immediate surgical intervention
Tend to cause higher prolactin levels than idiopathic hyperprolactinaemia
Tend to cause higher prolactin levels than idiopathic hyperprolactinaemia
PRL levels above 1000 mu/l are often due to adenoma; under 1009 iu/l, other causes such as compression, hypophysitis, null cell adenoma, etc. should be considered. Larger tumours are usually accompanied by higher blood levels.
Prolactinoma: most are less than 10 mm (microprolactinoma), rarely more than 10 mm (macroprolactinoma).
The compression of the optic chiasm results typically in a bitemporal hemianopia. MRI is more sensitive to small microadenomas than CT.
Generally the normal pituitary enlarges during pregnancy and a small but clinically non-significant enlargement is seen in microprolactinomas.
Rarely, tumours enlarge during pregnancy to produce headaches and visual defects.
Surgery is rarely now required even for large pituitary tumours, as these can be effectively treated with dopamine agonist therapy with rapid shrinkage, even with tumours that are compressing the optic chiasm.
Which of the following is true regarding oxytocin?
(Please select 1 option)
Causes milk ejection
Is a large polypeptide
Is released directly into the circulation from its site of production
Is synthesised in the posterior pituitary
Relaxes the uterus
Milk ejection
Oxytocin is synthesised in the hypothalamus and passes down the nerve axons to the posterior pituitary to be released into circulation.
The other hormone released by the posterior pituitary is antidiuretic hormone.
Oxytocin is involved in the control of smooth muscle contraction in the uterus and milk release from the lactating breast (the ‘milk ejection reflex’).
Oxytocin is a small peptide containing 9 amino acids.
Which of the following is correct in thyroid cancer?
(Please select 1 option)
Anaplastic carcinoma has a good prognosis if treated promptly
Follicular carcinoma spreads via the lymphatic system
Medullary carcinoma is associated with calcitonin
Papillary carcinoma is associated with MEN 1
The majority are follicular carcinomas
Medullary cancer associated with calcitonin
Anaplastic carcinomas of the thyroid are associated with poor prognosis.
Follicular carcinoma spreads via the blood stream.
MEN2 is associated with medullary carcinoma of the thyroid. Raised calcitonin levels are associated with medullary thyroid carcinoma.
Approximately 60% of patients presenting with a thyroid malignancy have a papillary carcinoma.
MEN1 is an inherited tumour syndrome, characterised by the development of tumours of the parathyroid, the anterior pituitary and the pancreatic islets.
Which of the following is caused by acute adrenal insufficiency? (Please select 1 option) Alkalosis Hyperglycaemia Hypernatraemia Hypokalaemia Hypotension
Hypotension
Patients with acute adrenocortical insufficiency (Addisonian crisis) may present with:
weakness nausea and vomiting abdominal pain hypotension, and fever. Biochemical findings associated with adrenocortical insufficiency include:
Hyponatraemia
Hyperkalaemia
Acidosis, and
Hypoglycaemia.
Which of the following is true regarding aldosterone?
(Please select 1 option)
Acts on specific cell surface receptors
Is produced in the zona reticularis of the adrenal cortex
Secretion decreases when sodium intake is reduced
Secretion is increased following haematemesis
Secretion is increased in phaeochromocytoma
haematemesis
Aldosterone is produced in the zona glomerulosa of the adrenal cortex and acts via intracellular steroid receptors to increase sodium reabsorption.
It is regulated by the renin/angiotensin system. Its release is therefore stimulated by hypovolaemia and blood loss, and is inhibited by increased sodium intake/hypertension.
In the carcinoid syndrome, when the primary tumour is in the terminal ileum, which of the following is correct?
(Please select 1 option)
Dementia is a recognised consequence
Fibrosis affecting the aortic valve implies the presence of a right to left inter-atrial shunt
Pellagra is a recognised manifestation
Removing the primary tumour prolongs life expectancy
There is a decreased incidence of peptic ulceration
Although dementia is associated with pellagra there are no reports of dementia with carcinoid syndrome and it seems that only the dermatitis features.
Lesions of the mitral valve usually cause a right-sided or pulmonary shunt.
Pellagra is a recognised manifestation. This is due to nicotinamide deficiency.
It is not the case that removing the primary tumour prolongs life expectancy. This is because it is the metastases that cause the problems.
Peptic ulceration is a recognised association with carcinoid syndrome.
Which of the following conditions is not associated with pancreatic enzyme deficiency? (Please select 1 option) Benign pancreatic cystadenoma Chronic pancreatitis Crohn's disease Cystic fibrosis Pancreatic carcinoma
Crohns
Causes of pancreatic enzyme deficiency include conditions causing pancreatic destruction such as
Pancreatitis
Cystic fibrosis
Pancreatic infiltrative disorders
Any condition capable of causing pancreatic duct obstruction.
Zollinger-Ellison (ZE) tumours are usually neuroendocrine, often small and cause gastrin excess. Exocrine dysfunction is not associated.
With regard to calcium metabolism and its control, which of the following is correct?
(Please select 1 option)
Calcitonin causes decreased renal excretion of calcium
Cholecalciferol is 25-hydroxylated in the liver
In plasma, calcium binding to protein is pH independent
The average daily absorption of calcium from the diet is 100 mmol
The major stimulant to parathyroid hormone secretion is a fall in the plasma unionised calcium concentration
Cholecalciferol is 25-hydroxylated in the liver
A fall in ionised calcium causes the chief cells of the parathyroid to secrete PTH.
Fifty percent of extracellular calcium occurs as non-ionised protein bound calcium.
The degree of ionisation increases inversely with pH.
Calcitonin causes increased renal excretion.
Glucocorticoid therapy is unlikely to cause which of the following? (Please select 1 option) Amenorrhoea Aseptic necrosis of the femoral head Hyperkalaemia Hypertrichosis Lymphopenia
Glucocorticoids and steroids may cause iatrogenic Cushing’s, with
Thin skin Ease of bruising Glucose intolerance/diabetes Hypertension Hypokalaemia Hirsutism Osteoporosis and it may result in
Hypogonadotrophic hypogonadism (hence amenorrhoea). Therapy may also be associated with aseptic necrosis of the femoral head.
Multiple endocrine neoplasia (MEN) type 2 consists of which of the following? (Please select 1 option) Adrenal cortex tumour Papillary carcinoma of the thyroid Parathyroid carcinoma Phaeochromocytoma Pituitary tumour
MEN type 2 is phaeochromocytoma, medullary cell carcinoma and hyperparathyroidism, often due to hyperplasia.
The RET proto-oncogene is usually a feature. Cortical adrenal adenomas are also recognised.
Pituitary tumours are a feature of MEN type 1.
Which of the following is correct regarding the basal metabolic rate (BMR)?
(Please select 1 option)
Decreases following major abdominal surgery
Increases with increasing age
Is greater in females than males
Is not related to lean body mass
Is the single largest component of energy expenditure
Is the single largest component of energy expenditure
BMR is higher in males than females, increases with increased muscle - that is, lean tissue - and declines with age.
Stress and illness cause an increase in BMR and a catabolic state.
Which of the following is untrue of 1,25-dihydroxycholecalciferol?
(Please select 1 option)
Binds to specific bone receptors
Decreases PTH release indirectly via effects on extracellular calcium concentrations
Exerts its effects via cell surface receptors
Increases intestinal absorption of phosphate
Reduces PTH release by direct effects on the parathyroid glands
Exerts its effects via cell surface receptors
1,25-dihydroxycholecalciferol is a steroid hormone with intra-cellular receptors.
Its effects on the parathyroids are direct and indirect.
With which of the following is hyperchloraemic metabolic acidosis associated? (Please select 1 option) An elevated anion gap Hypothyroidism Pancreatic fistula Salicylate poisoning Secondary hyperaldosteronism
Pancreatic fistula
Secondary hyperaldosteronism often found in association with cirrhosis is associated with a raised anion gap.
Hyperchloraemic acidosis would be associated with a normal/reduced anion gap.
Hyperparathyroidism is associated with this disorder.
A pancreatic fistula is associated with bicarbonate losses.
Which of the following statements is correct regarding papillary carcinoma of the thyroid gland?
(Please select 1 option)
After destruction of the normal thyroid tissue by tumour there is still uptake of iodine
Has a better prognosis than follicular carcinoma
Has a good response to chemotherapy
Is associated with hypocalcaemia in 20% of cases
Is the second most common cause of thyroid malignancy
Has a better prognosis than follicular carcinoma
Most tumours are ‘cold’ on radioisotope scan (123I or 99mTc). Some 20% will have normal or increased uptake. About 50% of tumours retain some ability to concentrate iodine. This explains the response of metastases to 131I. Radioactive iodine can be used to ablate any remaining thyroid tissue after total thyroidectomy for well-differentiated tumours larger than 1 cm diameter.
Prognosis - 10-year survival:
Papillary carcinoma 80% Follicular 60% Medullary (C cell) 50% Anaplastic 0%. Chemotherapy (doxorubicin) is of little benefit. The mainstay of treatment is 131I treatment. External beam radiotherapy may help in the treatment of bone metastases.
Medullary carcinomas (from the parafollicular C cells of the thyroid) secrete calcitonin. About 20% of these are associated with multiple endocrine adenomatosis (MEA) II a or b.
Papillary carcinoma is the commonest thyroid malignancy (60%). The others are:
Follicular (25%)
Anaplastic (10%)
Medullary (C cell) (5%)
Lymphoma about 1%.
Which of the following is correct regarding the syndrome of inappropriate antidiuretic hormone secretion (SIADH)?
(Please select 1 option)
A cause of dependent oedema
A complication of carbamazepine treatment
Typically associated with squamous cell bronchial carcinoma
Treated with furosemide
Typically associated with a serum osmolality of 295-315 mosm/kg (normal range 278-305)
Carbamazepine treatment
SIADH is associated with
Drugs, such as carbamazepine Selective serotonin reuptake inhibitors (SSRIs) Head injury Tumours Pneumonia and typically,
Oat cell, rather than squamous cell lung cancer.
It may respond to demeclocycline (not furosemide).
It produces a euvolaemic hyponatraemia and dependent oedema is not a feature (if present it makes the diagnosis less likely).
Plasma osmolality is low and urine sodium and osmolality are high.
Of which of the following is hyponatraemia not a recognised complication?
Carbenoxolone therapy Cerebral contusion Congestive heart failure Hepatocellular failure Major surgery
Carbenoxolone therapy
Hyponatraemia can be classified as a hypovolaemic, euvolaemic or hypervolaemic state.
Hypovolaemic state is due to marked dehydration with excessive salt losses, for example, vomiting or Addison’s disease.
Euvolaemic state typically reflects syndrome of inappropriate secretion of antidiuretic hormone (SIADH).
Hypervolaemic state is due to conditions such as congestive cardiac failure (CCF), cirrhosis, nephrotic syndrome and myxoedema.
Carbenoxolone causes pseudohyperaldosteronism with hypertension, hypernatraemia and hypokalaemia.
Major surgery, pneumonia, subarachnoid, meningitis and injury (as well as drugs) can induce SIADH.
A 60-year-old woman presents to the surgical outpatient clinic with ulceration over the tips of the toes in her left foot and a large ulcer over her right heel. She also complains of paraesthesia in both feet.
The ankle-brachial pressure indices are 1.05 on the right and 1.2 on the left. On neurological assessment, proprioception and vibration sense are reduced.
Choose the single most appropriate diagnosis.
(Please select 1 option)
Hypertensive ulcer (Martorell’s ulcer)
Neuropathic ulcer CorrectCorrect
Pyoderma gangrenosum
Squamous cell carcinoma
Vasculitic ulcer
This patient is most likely to have a neuropathic ulcer, usually resulting from peripheral sensory neuropathy secondary to diabetes mellitus.
The other causes for altered sensory neuropathy leading to neuropathic ulcers include
Spinal cord injuries Spina bifida Syringomyelia Alcohol abuse and Leprosy. The usual sites in the lower limb for neuropathic ulceration are the head of the metatarsals, interdigital clefts, heel (calcaneum) and the lateral malleolus.
In diabetic patients, the ankle-brachial pressure indices may be falsely elevated, even in those with major vessel disease. This is due to calcification of the vessel walls and medial sclerosis.
Neurological assessment may reveal altered sensation, including proprioception and two point discrimination in the foot or toes, and reduced vibration sense.
Which of the following is not a classical feature of an addisonian crisis?
(Please select 1 option)
A high serum glucose This is the correct answerThis is the correct answer
A low plasma sodium IncorrectIncorrect answer selected
A raised blood urea
Fever
Occurrence during pregnancy
An addisonian crisis may be precipitated by any stressful event. Frequently this is an infection.
Pregnancy is a recognised cause. This may be due to increasing metabolic demands or vomiting.
The features of an addisonian crisis include
Hypotension Hyponatraemia Hyperkalaemia Hyperuricaemia Hypoglycaemia.
