Calcium and PTH disorders Flashcards
what is the body’s response to low serum calcium levels?
secrete PTH from the parathyroid glands
what is the impact of high conc Calcitriol on the parathyroid glands
calcitriol will cause negative feedback of PTH release
3 effects of Calcitriol (vitamin D3) ??
bone resorption
renal re-absorption
more absorption in gut
what is calcidiol?
VD2 - inactive form of vitamin D. obtained in diet, or from conversion of calciferol in liver
how is vitamin D3 made in the skin?
UV rays causes conversion of a cholesterol molecule –> Vitamin D3
what type of cell are osteoclasts?
macrophages!!
how do osteoclasts resorb bone?
they release HCl acid which frees up Calcium and phosphate into the blood
what do osteoblasts do?
they build up bone – they give it minerals and collegen
describe signs of acute hypercalcaemia
patient who is severely dehydrated (due to polyuria) causing confusion and thirst
why do hyperCa patients get renal stones?
from continuous reabsorption of calcium in the nephrons
what enzyme changes vitamin D2 –> active D3?
1-alpha-hydroxylase
hypercalcaemia
- high?
- emergency?
over 3 mmol/ L
over 3,75 mmol / L
hypercalcaemia with high PTH and high urinary excretion of Calcium?
primary or tertiary hyperparathyroidism (lots of retention)
hypercalcaemia with high PTH and low urinary Ca excretion?
Familial Hypocalciuric hypercalcaemia (FHH)
hypercalcaemia caused by CaSR mutation?
FHH - autosomal dominant muration
hypercalcaemia with low PTH and high ALP levels?
Conditions causing increased bone turnover!!!
- Eg. metastasis, thyrotoxicosis
hypercalcaemia with low PTH and low ALP levels? (3)
- myeloma
- Vitamin D excess - many causes
- “Milk-Alkali”
2 signs of hypercalcaemia not included in stones, moans etc?
- hypertension
2. proximal myopathy
example of an “abdominal groan”?
pancreatitis
serum levels for hypocalcaemia?
less than 2.1 !!
what is Chvostek sign for hypocalcaemia?
facial twitching induced by tapping the facial nerve (anterior to the ear)
what is Trousseau sign for hypocalcaemia??
spasm of the forearm and hand induced by 3 minutes of a blood pressure cuff
common signs of hypocalcaemia?
hands = paraesthesia
SOB = due to bronchospasm
Muscle cramps
Fitting
what surgery is the #1 cause of hypocalcaemia?
post-surgical-hypoparathyroidism when part of gland is removed !!
classic symptoms of hypomagnesium?
Tremor, poor coordination, muscle spasms, personality changes, and nystagmus. Complications may inc seizures / cardiac arrest..
what is the cellular function of Mg?
to allow Calcium to be released from cells
are levels of PTH low or high in pseudohypoparathyroidism?
they are HIGH : but the mutation causes resistance to PTH
pseudohypoparathyroidism levels…
PTH = low / high ?
Calcium = low / high ?
PTH is high (because)
Ca is low
what is the classic sign of pseudohypoparathyroidism in the hands?
shortened 4th and 5th fingers
pseudohypoparathyroidism signs (type 1a)
fingers :
weight:
cognitive:
short 4th + 5th fingers
obese
learning disability
what is pseudo-pseudo-hypoparathyroidism?
the phenotypical changes WITHOUT the biochemical markers (normal PTH and normal Ca)
what does the GNAS1 mutation cause?
pseudo-parathyroidism
susan has high PTH levels, low Ca but no symptoms - what is this?
This is pseudohypoparathyroidism type 1b !!
