Endocrinology Flashcards
What is the role of calcium in the body?
- regulation of voltage-gated ion channels in neurones and muscle
- mineralisation and strengthening of bones
- facilitation of blood clotting
What are the causes of abnormalities in calcium homeostasis?
Dysregulation in:
- PTH production
- vitamin D production
- renal dysfunction
- metabolic bone disease
- gut dysfunction and dietary deficiency of calcium, phosphate or magnesium
What is the homeostatic response to a decrease in serum calcium?
Increased PTH production. Increased calcium reabsorption in nephrons. Increased bone resorption. Increased calcium absorption.
What measures can be taken to help prevent nocturnal hypoglycaemia?
- take a bedtime snack regularly
- patients that take twice daily mixed insulin can separate their evening dose and take the intermediate insulin at bedtime rather than before supper
- reduce the dose of soluble insulin before supper since its effects persist well into the night
- change to rapid-acting insulin analogue with a long-lasting insulin analogue at night
- changing to an insulin infusion pump that can be programmed to deliver lower doses of insulin at time of night when a patient has been experiencing hypoglycaemia.
Why is there a poor correlation between urine tests and simultaneous blood glucose?
- changes in urine glucose lag behind changes in blood glucose
- mean renal threshold is around 10 mmol/L but the range is wide form 7 to 13. Threshold rises with age.
- urine tests can give no guidance concerning blood glucose levels below renal threshold.
What is ketonuria?
Detectable ketone levels in the urine.
can occur in fasted non-diabetics
What is ketosis?
Elevated plasma ketone levels in the absence of acidosis.
What is diabetic ketoacidosis?
A metabolic emergency in which hyperglycaemia is associated with a metabolic acidosis due to greatly raised (>5 mmol/L) ketone levels. Seen in T1DM.
What is a hyperosmolar hyperglycaemia state?
A metabolic emergency in which uncontrolled hyperglycaemia induces a hyperosmolar state in the absence of significant ketosis. Seen in T2DM.
What is lactic acidosis?
A metabolic emergency in which elevated lactic acid levels induce a metabolic acidosis. In diabetic patients, it is rare and associated with biguanide therapy.
Briefly describe the pathogenesis of diabetic ketoacidosis.
Insulin deficiency leads to uncontrolled catabolism. Gluconeogenesis in the liver is no longer suppressed and hence there is increased glucose production. This causes hyperglycaemia and glycosuria leading to osmotic diuresis. Simultaneously, rapid lipolysis occurs forms more free fatty acids that are converted to ketones by hepatocytes. This leads to acidosis and vomiting. There is fluid and electrolyte depletion causing renal hypoperfusion and impaired excretion of ketones and hydrogen ions.
What are the clinical features of diabetic ketoacidosis?
prostration, hyperventilation (Kussmaul breathing), nausea, vomiting, abdominal pain, confusion, stupor, evidence of dehydration, ketone breath, low body temp, dry skin.
What are the principles of management of DKA?
- replace fluid losses
- replace electrolyte losses
- restore acid-base balance
- replace deficient insulin
- monitor blood glucose closely
- seek the underlying cause
Which hormone is affected in acromegaly and how?
Hypersecretion of growth hormone
What is the role of the growth hormone?
GH stimulates skeletal and soft tissue growth
What is an excess of growth hormone before puberty called?
Gigantism
What is an excess of growth hormone after puberty called?
Acromegaly
What happens to bone growth at puberty?
Epiphyseal fusion
Describe the onset of acromegaly in one word.
Insidious
What inhibits growth hormone?
Somatostatin
What factors stimulate growth hormone release?
Stress, sleep, exercise
What are the sporadic causes of acromegaly?
- Somatotroph adenoma
- Ectopic GH secretion
- Hyperplasia due to GHRH excess
What are the genetic causes of acromegaly?
- Familial acromegaly
2. Multiple endocrine neoplasia (MEN1)
What is familial acromegaly?
It is an autosomal dominant inherited form of acromegaly that has incomplete penetrance and leads to gigantism.
What are the symptoms of acromegaly?
- Change in facial appearance
- Headache
- Visual disturbance
- Deep voice
- Goitre
- Fatigue
- Daytime drowsiness
- Weight gain
- Sweating
- Arthralgia
- Amenorrhoea/oligomenorrhoea
- Impotence/ decreased libido
What are the signs of acromegaly?
- Prominent supraorbital ridge
- Prognathism
- Interdental separation
- Macroglossia
- Visual field defects
- Hirsutism
- Spade-like hands and feet
- Carpal tunnel syndrome
- Hypertension
- Proximal myopathy