Flashcards in Hypercalcaemia Deck (13):
normal serum control
40% is bound to albumin therefore inactive
2.2-2.6 (inc albumin)
in acidotic states, is calcium increased or decreased?
increase ionised Ca, by reduced albumin binding
in alkalotic states, is calcium increased or decreased?
decrease ionised Ca, by increased albumin binding
how is calcium regulated?
diet: gut absorption (vit D)
bones: 99% of Ca
how is calcium linked to phosphate?
decrease Ca = increase phosphate
what hormones are involved in calcium regulation?
PTH (chief cells)
vit D (gut)
when is PTH secreted?
PTH is secreted when:
Ca is LOW
vit D is LOW
phosphate is HIGH
how does calcitonin regulate Ca?
secreted by parafollicular/C cells of thyroid
acts to decrease Ca by antagonism of effects of PTH on bone
PTH/vit D levels are adjusted in response to calcitonin levels
how does PTH regulate Ca?
bone: stimulates Ca REABSORPTION
kidney: renal tubular Ca ABSORPTION
GI: indirectly stimulating GI Ca ABSORPTION by INCREASING vit D activation by the kidney
increases renal phosphate EXCRETION
when is vit D secreted?
when Ca is LOW
when is calcitonin secreted?
when Ca is HIGH
97% primary hyperparathyroidism (high PTH) or malignancy (low PTH)
Renal insufficiency (tertiary hyperPTH)
Iatrogenic (AdCal - OP supplement)
Other endocrinopathies (Addisons)