Disorders of Calcium Homeostasis Flashcards
what rhyme is used for the symptoms of hypercalcaemia
stones
bones
abdominal moans
psychic groans
clinical manifestations of hypercalcaemia
muscle weakness
anorexia
nausea
mood change
depression
impaired water concentration in kidneys
renal stone formation
bone disease
abdominal pain
ECG changes - shortened QT interval, AF
what ECG changes are associated with hypercalcaemia
shortened QT interval
AF
causes of factitious hypercalcaemia
venous stasis (e.g. due to tourniqué)
dehydration
IV albumin
what is factitious hypercalcaemia
high Ca due to high plasma albumin
non-pathological
what is the difference between primary, secondary and tertairy hyperparathyroidism
1 - autonomous and innappropriate overproduction of PTH leading to hypercalcaemia
2 - appropriate increase in PTH in response to hypocalcaemia
3 - where a secondary overactive gland becomes overactive
cell appearance in biopsy in normal parathyroid compared to abnormal
normal - heterogenous cells
abnormal - homogenous cells
what features could be seen in xrays of someone with hyperparathyoridism
kidney stones
osteopenia
what will Ca and PTH levels be in primary hyperparasthyroidism
raised Ca
inappropriately raised PTH (should be low if Ca is high)
serum phosphate and bicarbonate levels in primary hyperparathyroidism
low due to increased renal excretion
what can be used for more difficult diagnoses of primary hyperparathyroidism
parathyroid imaging scan - using radioisotope
treatment of primary hyperparathyroidism
acutely rehydration and drugs
surgery to remove tumour
unless mild or can’t tolerate surgery - then drugs and monitoring of Ca and PTH levels
drugs for hypercalcaemia
bisphosphonates
furosemide
calcitonin (short term)
glucocorticoids
most common cause of hypercalcaemia in hospitalised patients
malignant disease
why is malignant disease a common cause of hypercalcaemia
endocrine factors secreted by malignant cells act on the bone
metastatic tumour deposits in bone locally which stimulates bone resorption via osteoclast activation
most common type of cancer to cause hypercalcaemia
lung
breast
multiple myeloma
(more likely to metastasise to bone)
what endocrine factors are involved in malignant hypercalcaemia
solid tumours may secrete PTH-related peptide which is similar in structure and function to PTH
some tumours synthesise calcitriol
clinical manifestations of hypercalcaemia of malignancy
abundance of plasma cells in biopsy
pepperpot skull due to bone resorption
weak bones which break easily
Ca, PTH, phosphate and alkaline phosphatase levels in malignant hypercalcaemia
Ca high
PTH low
phosphate high
alkaline phosphatase high
treatment of malignant hypercalcaemia
rehydration
drugs to lower calcium (e.g. bisphosphonates)
treat cancer
causes of hypercalcaemia
primary hyperparathyroidism
cancer
granulomatous disease (e.g. sarcoidosis)
exogenous vitamin D excess
FHH
drugs (e.g. lithium, thiazide diuretics)
endocrine disease (e.g. thyrotoxicosis, Addison’s)
immobilisation
what part of the body is usually affected in sarcoidosis
lungs (90%)
skin (10%)
Ca and PTH levels in sarcoidosis
Ca - high
PTH - normal
how does sarcoidosis cause high Ca
vitamin D is hydroxylated in the granulomas
so more Ca absorbed
what does FHH stand for
familial hypocalciuric hypercalcaemia
what is FHH
Ca sensor on PT glands less sensitive to Ca suppression
so altered set point for PTH and Ca interaction
PTH levels high normal or slightly high
high plasma Ca
low urine Ca
clinical manifestations of hypocalcaemia
numbness
parastheasia
anxiety
fatigue
muscle cramps
carpo-pedal spasm
bronchial or laryngeal spasm
seizures
personality change
mental confusion
psychoneurosis
impaired intellectual ability
ECG changes (long QT interval)
eye problems
what characteristic do hypocalcemia symptoms have
due to increased muscular excitability
what is Chvostek’s sign and what is it a sign of
contraction of eye mouth or nose when tapping along facial nerve
hypocalcaemia
what is Trousseau’s sign and what is it a sign of
anterior lower arm muscles contracting when the brachial artery is occluded for 3 minutes
hypocalcaemia
what is factitious hypocalcaemia
low calcium as a consequence of low plasma albumin
causes of facitious hypocalcaemia
malnutrition/malabsorption (protein deficiency in diet)
liver disease (reduced liver synthesis)
nephrotic syndrome (albumin lost in urine)
causes of hypocalcaemia
vitamin D deficient/lack of vitamin action
- lack of sunlight
- inadequate dietary source
- malabsorption
- CKD
why does low vit D cause bone disease
low vit D → low Ca → PTH rise → increased bone resorption
also bone that is laid down is not adequately calcified
Vit D, Ca, PTH, phosphate and ALP levels in vit D deficiency
vit D low
Ca low
PTH high
phosphate low
ALP raised
rickets is called what in adults
osteomalacia
causes of hypoparathyroidism
surgical damage/removal
suppressed secretion (e.g. low Mg or maternal hypercalcaemia)
inherited developmental parathyroid problems
genetic disorders
Ca and PTH in hypoparathyroidism
low Ca
inappropriately low PTH
treatment of hypocalcaemia
IV/oral calcium
IM or oral vit D
close monitoring of plasma calcium
are there changes to Ca in osteoporosis
no
how is osteoporosis investigated
DEXA scan
histology of bone in osteoporosis vs osteomalacia
osteoporosis - normal formation but just less of it
osteomalacia - uncalcified osteiod (bone matrix)
