Endocrine disorders Flashcards
(25 cards)
What is the action of PTH?
Increase [Ca2+] in the blood:
- Bone: osteoclasts break down bone, release Ca2+
- Kidney: calcium reabsorption
- GIT: absorption increased (activate vitamin D)
Decrease [phosphate] in the blood (small net decrease):
- Kidney: increased excretion/reduced reabsorption
- GIT: increased uptake (vitamin D)
- Bone: increased osteoclast activity –> release into blood
What is the action of calcitonin?
Decreases serum Ca2+
Where is calcitonin secreted?
C-cells/parafollicular cells of the thyroid gland
What is primary hyperparathyroidism?
Increased PTH due to intrinsic abnormality of the parathyroid glands: usually a single adenoma –> hypercalcaemia
Most common cause of hypercalcaemia in non-hospital population
Causes of hypercalacaemia?
- Disorders of parathyroid gland: primary hyperparathyroidism, long term lithium Rx
- Malignancy: haematological, bone mets, paraneoplast syndrome
- Vit D disorders: hypervitaminosis D
- High bone turnover: Thyrotoxicosis, long-term bed rest, thiazides, multiple myeloma, vitamin A
- Renal disorders: Tertiary hyperparathyroidism
Clinical features of hypercalcaemia?
- Bones: pathological fractures, musculoskeletal pain, radiological/densitometric abnormalities
- Stones: Renal calculi
- Groans: Abdominal pain (renal stones)
- Moans: Depression, apathy/tiredness, confusion, delirium
- Asymptomatic
What is secondary hyperparathyroidism?
Physiological/appropriate secretion of excess levels of PTH due to hypocalcaemia, most commonly secondary to chronic kidney disease and hypovitaminosis D (lack of sunlight exposure, or dietary intake)
What is tertiary hyperparathyroidism?
Long-standing secondary hyperparathyroidism which has progressed to an autonomous hyperplastic parathyroid gland/s, which continue to secrete PTH at high levels following resolution of secondary cause
What are the islet cell tumours of the pancreas (in order of incidence)?
Insulinoma - B cells
Gastrinoma - D cells
Gulcagonoma - A cells
Which cells may undergo neoplastic change to form a gastrinoma?
Gastrin-producing cells of the pancreas and duodenum, but NOT the antrum of the stomach
What is the classic triad of features of Zollinger-Ellison syndrome?
- Recurrent peptic ulceration
- Marked acid secretion
- Gastrinoma
How to diagnose Zollinger-Ellison syndrome?
Elevated serum gastrin + raised basal fasting acid secretion
Features suggestive of Z-E syndrome?
MURDR MEN:
- Multiple ulcers
- ulcers in Unusual sites
- Recurrent ulcer
- ulcer + Diarrhoea
- Refractory ulcer
- ulcer + MEN syndrome
Causes of hypoglycaemia?
- Anti-diabetic medications
- Liver disease
- Alcohol
- Post-gastrectomy dumping
- Insulinoma
MEN 1 syndrome?
- Pituitary: acromegaly/prolactinoma
- Pancreas: insulinoma/gastrinoma
- Hyperparathyroidism
MEN 2a syndrome?
- Medullary thyroid cancer
- Phaeochromocytoma
- Hyperparaythroidism
MEN 2b syndrome?
- Medullary thyroid cancer
- Phaeochromocytoma
- Marfanoid habitus
- Mucosal neuromas
Clinical features of Cushing’s syndrome?
- Central obesity
- Weakness/proximal myopathy
- Hypertension
- Skin changes: bruising/thin skin, acne, hirsuitisn, striae
- Psychiatric changes: mental slowing, depression
- Oligo-/amenorrhoea/impotence
- Osteoporosis
- Thirst/polyuria
- Glucose intolerance
Common causes of Cushing’s disease?
- Steroid administration/iatrogenic - common
- Cushing’s Disease (pituitary) - 70%
- Ectopic ACTH (paraneoplastic) - 10%
- Adrenal ademona/carcinoma - 20%
What is Cushing’s syndrome caused by, hormonally?
Excess adrenal cortical hormones - cortisol
What is Conn’s syndrome?
Aldosterone-secreting adenoma of the adrenal cortex causing hypokalaemia and hypertension
What are carcinoids?
Indolent neuroendocrine tumours
Found anywhere in the GIT (particularly the ileum, appendix), lung, thymus, ovaries
What is carcinoid syndrome?
When carcinoid tumour metastasizes past the liver (metabolic filter) and secretes metabolic products, causing systemic effects
Clinical features of carcinoid syndrome?
Excessive production of a range of hormones, most notably serotonin, causing:
- Flushing (episodic, lasts 30 seconds, involves face, neck, chest, turning red/purple, mild burning sensation)
- Severe diarrhoea
- Wheezing
- Abdominal cramping
- Peripheral oedema
