27 Questions
What does a family history of hypercalcaemia raise the possibility of?
Familial hypocalciuric hypercalcemia
What do high plasma phosphate and alkaline phosphatase levels accompanied by renal impairment suggest?
Tertiary hyperparathyroidism
What can hypercalcaemia cause that may result in hyperuricaemia and hyperchloraemia?
Nephrocalcinosis
What is the net effect of prolonged exposure of bone to high levels of PTH?
Mobilisation of calcium into the extracellular fluid
What is the effect of pulsatile release of PTH on bone?
Causes net bone gain
What is the most common cause of hypercalcaemia?
Malignancy
What are the classic symptoms associated with primary hyperparathyroidism?
Bones, stones and abdominal groans
What is the role of parathyroid hormone (PTH) in regulating calcium and phosphate homeostasis?
Enhancing calcium absorption from the gut by promoting the conversion of 25-hydroxyvitamin D to the active metabolite
How do the parathyroid chief cells respond to changes in calcium concentrations?
By directly interacting with the calcium-sensing receptor located on the cell surface
What happens to PTH secretion when serum ionized calcium levels fall?
It rises
What is the main function of PTH on the skeleton?
Increasing osteoclastic bone resorption and bone formation
What is the most likely diagnosis if PTH levels are detectable or elevated in the presence of hypercalcaemia?
Primary hyperparathyroidism
What does a biochemical presentation similar to primary hyperparathyroidism with low urinary calcium excretion indicate?
Familial hypocalciuric hypercalcemia
What condition is suggested by high plasma phosphate and alkaline phosphatase levels accompanied by renal impairment?
Tertiary hyperparathyroidism
What is the recommended initial medical management for severe hypercalcaemia?
IV 0.9% saline 2–4 L/day
What is the duration of action of calcitonin in the treatment of hypercalcaemia?
4 weeks
In the medical management of severe hypercalcaemia, what is the alternative option for patients with refractory hypercalcaemia if zoledronic acid is not effective?
Denosumab initial dose 60 mg SC
What is the most common cause of hypocalcaemia?
Low serum albumin with normal ionised calcium concentration
How does magnesium depletion cause hypocalcaemia?
By impairing the ability of parathyroid glands to secrete PTH
What is the effect of hypomagnesaemia on serum phosphate levels?
Causes variable serum phosphate levels
How should calcium be adjusted in the presence of hypoalbuminaemia?
Increase by 0.02 mmol/L for every 1 g/L reduction in albumin below 40 g/L
What is the characteristic phenotype associated with pseudohypoparathyroidism?
High serum phosphate and alkaline phosphatase levels accompanied by renal impairment
What is the characteristic triad of symptoms seen in children with tetany?
Carpopedal spasm, stridor, and convulsions
What is the latent tetany detected by eliciting Trousseau’s sign?
Inflation of a sphygmomanometer cuff on the upper arm followed by carpal spasm within 3 minutes
What may prolonged hypocalcaemia and hyperphosphataemia cause in association with hypoparathyroidism?
Calcification of the basal ganglia, grand mal epilepsy, and psychosis
What is the recommended initial management for severe hypocalcaemia?
$10–20 mL 10% calcium gluconate IV over 10–20 mins
What may hypocalcaemia associated with hypophosphataemia cause in children and adults?
Rickets in children and osteomalacia in adults
Explore the role of parathyroid hormone (PTH) in regulating calcium and phosphate levels, as well as its impact on vitamin D metabolism. Learn about the consequences of altered PTH function in gut and renal disease, metabolic bone diseases, disorders of the parathyroid glands, hypercalcemia, and hypocalcemia.
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