Calcium Dysregulation Flashcards
What hormone(s) increases calcium levels?
Vitamin D
Parathyroid hormone
What hormone(s) decreases calcium levels?
Calcitonin
How is vitamin D mentabolised?
UVB light 7 dehydrocholesterol Pre vitamin D3 Vitamin D3 OR Vitamin D2 from diet 25 hydroxylase in liver makes it 25(OH) cholecalciferol 1 alpha hydroxylase in kidney makes it 1,25 (OH)2 cholecalciferol= calcitriol
What is the active form of vitamin D called?
Calcitriol
What vitamin D enzyme is found in the liver?
25 hydroxylase
What vitamin D enzyme is found in the kidney?
1 alpha hydroxylase
What are the effects of calcitriol?
Increases osteoblast activity
Increases calcium reab in gut and kidney
Decreases phosphate excretion in kidney
Increases phosphate absorption in gut
What are the effects of PTH?
Increases calcium resorption from bone
Increases calcium absorbtion in gut and kidney
Increases phosphate absorbtion in gut
Increases phosphate excretion in the kidney
Increases 1 alpha hydroxylase activity
What does FGF23 do?
Blocks sodium phosphate co transporter in PCT like PTH, encouraging excretion of both in the urine
It also inhibits calcitriol
What is calcitriol inhibited by?
FGF23
How does hypocalcaemia present?
Cats go numb: Convulsions Arrythmias Tetany Paraesthesia
What are the 2 signs of hypocalcaemia?
Chovstek’s sign- facial paraesthesia when you tap the zygomatic branch of the facial nerve
Trousseau’s sign- carpopedal spasm
What are the causes of hypocalcaemia?
Low PTH levels (surgical, autoimmune, magnesium deficiency, congenital)
Low vitamin D (diet deficiency, UV light etc)
How does hypercalcaemia present?
Stones- renal effects (kiney stones)
Abdominal moans- GI effects (anorexia, nausea, dyspepsia)
Psychic groans- CNS effects (fatigue, depression etc)
What are the causes of hypercalcaemia?
Primary hyperparathyroidism- too much PTH
Malignancy- produce local factors to activate osteoclasts or make peptide that acts on PTH receptors
Vitamin D excess