Calcium homeostasis Flashcards
What hormone is secreted by the parathyroid glands and involved in Calcium homeostasis?
PTH, parathyroid hormone
What are the symptoms of Hypercalcaemia?
Stones, groans, bones, psychic moans
- thirst
- dehydration
- confusion
- polyuria
- fractures
- depression
- hypertension
Why do granulomatous diseases cause hypercalcaemia?
TB and sarcoidosis
-produce vitamin D
Name 4 causes of Hyoercalcaemia:
- Primary Hyperparathyroidism
- Malignancy
- Granulomatous disease
- Familial Hypocalciuric Hypercalcaemia
What drugs can cause hypercalcaemia?
Thiazide diuretics
Vitamin D
How is hypercalcaemia treated?
- rehydrate with IV fluids
- flush Ca out with loop diuretics (NOT thiazide)
- bisphosphonates
Why is Calcium raised in Familial Hypocalciuric Hypercalcaemia? How is diagnosis confirmed?
- Calcium detection level by Calcium Sensing Receptors in parathyroid glands is raised
- negative feedback occurs at higher plasma calcium
If PTH and serum Ca are raised, confirm FHH by checking if urine calcium
-if low, it’s FHH
What are the symptoms/signs of Hypocalcaemia?
- loss of sensation in peripheries
- muscle cramps and weakness
- fits
- QT prolongation on ECG
Name 3 causes of Hypocalcaemia.
- Hypoparathyroidism
- Vitamin D deficiency
- Chronic renal failure
What is the treatment of acute Hypocalcaemia?
Emergency!
-IV calcium gluconate
What are the causes of Hypoparathyroidism?
- congenital (DiGeorge syndrome - congenital absence)
- Surgical/radiotherapeutic /autoimmune desctruction
- Hypomangesaemia
Why is PTH release inhibited in Hypomagnasaemia?
- Calcium release from cells is Mg-dependent
- Intracellular calcium is high
- PTH release is inhibited by high Ca
What is the cause of Pseudohypoparathyroidism?
PTH resistance
-does not induce desired resorption/absorption of Ca
Describe the biochemistry of Primary Hyperparathyroidism?
Calcium: high
PTH: high
ALP: normal
Phosphate: low
Describe the biochemistry of bone malignancy.
Calcium: high
PTH: low (suppressed)
ALP: v. high
Phosphate: normal
Describe the biochemistry of Familial Hypocalciuric Hypercalcaemia.
Calcium: high (mild) PTH: normal/mild elevation ALP: normal Phosphate: normal/mild elevation Urine Calcium: low
Describe the biochemistry of Hypoparathyroidism.
Calcium: low
PTH: low
ALP: normal
Phosphate: normal/mild elevation
Describe the biochemistry of osteomalacia.
Calcium: low
PTH: high
ALP: v. high
Phosphate: low
Describe the biochemistry of Paget’s disease?
Calcium: normal (slightly high)
PTH: normal
ALP: High
Phosphate: normal
