Parathyroid / Hypercalcaemia Flashcards
hyperparathyroidism
high level of PTH (parathyroid hormone)
three types
primary
secondary
tertiary
physiology of the PTH
four glands in four corners of the parathyroid gland
chief cells produce PTH in response to low blood ca2+ concentration.
PTH raises blood ca2+ by the following mechanisms:
1) increase the absorption of ca2+ from intestine
2) increase reabsorption in the kidneys (less is secreted in the urine)
3) increase osteoclast activity in the bones (more is broken down so ca2+ is released into the blood)
vitamin D and PTH
body creates in response to sunlight. can be obtained through food / supplementation
PTH acts on vitamin D to convert it into its active forms
Vitamin D works by acting on all processes to increase absorption of ca2+from kidneys, intestines and bones = raise blood ca2+ level
primary hyperparathyroidism
uncontrolled PTH being produced by a tumor of the parathyroid gland.
increased absorption of ca2+ leading to hypercalcaemia.
(too much PTH so it’s causing too much of GI absorption / renal reabsorption and bone break down which leads to excessive ca2+ in the blood)
tx: surgical removal of tumor
secondary hyperparathyroidism
causes:
insufficient vitamin D
chronic renal failure
= reduced absorption, resorption and osteoclast of calcium which leads to hypocalcaemia.
as a result, the PTH react to the low level of ca2+ by excreting more PTH to try and compensate.
overtime the total number of cells in the parathyroid gland increase (hyperplasia)
serum ca2+ low/normal
PTH hormone high
treat: correct underlying cause (vitamin D, renal transplant)
tertiary hyperparathyroidism
this occurs when 2’ hyperparathyroidism continues for a long time which leads to hyperplasia of the glands. the baseline amount of PTH increases dramatically.
when you treat the 2’ hyperparathyroidism, the levels remain HIGH
serum ca2+ high
PTH high
treatment: surgical removal of bulky glands leaving just enough tissue to get PTH
summary of hyperparathyroidism
1’ tumor causing high PTH which leads to high Ca2= surgical tx
2’ deficiency in vit d/ chronic kidney disease. high PTH, serum ca2+ low or normal. tx vit D deficiency or renal transplant
3’ hyperplasia of parathyroid glands after secondary. high PTH, high ca2+. tx: surgical
causes of hyperpcalcaemia
CHAMPS
calcium supplementation cancers myeloma/bone mets hyperparathyroidism (1') Addison's/acromealy ilk alkali syndrome pagets sarcoidosis
corrected calcium equation
corrected calcium = serum calcium + 0.02 (40-albumin)
give IV saline and re-check ca2+.
management of hypercalcaemia
> 3 mmol/l
adequate rehydration 3-4L saline/day
IV bisphosphonate (pamidronate)
identify cause.
