Ca Homeostasis Flashcards
A 40-year- old lady post-total thyroidectomy for follicular carcinoma. POD4 her serum Calcium came 0.7 mmol/L.
A 40-year- old lady post-total thyroidectomy for follicular carcinoma. POD4 her serum Calcium came 0.7 mmol/L.
Check list
Pt underwent total thyroidectomy 36 hrs ago. Complains of numbness and tingling of lips, hands and feet. Her Blood results are available.
Q. How’s calcium transported in plasma and which part is physiologically active?
50% bound to plasma ptn mainly albumin and 50% are free ionized Ca and this’s the active component.
Q. which substances control the Ca level? Mention 3
Calcitonin – Vit D3 – PTH
Q. What are the 3 mechanisms by which the PTH raises Serum Ca?
- Direct action on bone by increasing resorption and mobilise Ca
- incr. reabsorption of Ca from DCT by acting on kidneys
- Stimulate Formation of Active VIT D in kidney which increase absorption of Ca from small intestine.
Q. What’s the effect of PTH on Plasma Ph level? What’s the mechanism?
Decrease it by; decrease its reabsorption in PCT
Q. outline how Vit D3 produced and metabolized?
Dehydrocholesterol is a cholesterol precursor that’s transformed into Vit D3 in skin by the action of Sunlight and also ingested in diet.
–Metabolised in liver to produce 25-hydroxycholecalciferol (Calcidiol)
–Then metabolized in kidney to active 1,25-Dihydroxycholecalciferol (Active Vit D)
Q. what are the actions of Vit D3?
–Incr. Absorption of Ca from Gut.
–Facilitate reabsorption of Ca from Kidneys and
–Incr. activity of osteoblast which imp for the calcification of the bone matrix.
Q, what are the main physiological roles of ionized Ca?
-Nerve conduction
–Muscle contraction
–Blood Coagulation
–Release of hormons mediates Insulin secreation
–Cardiac contractility
–Complement activation
Q. In this scenario, what’s the most likely cause of HypoCa?
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Devascularization or excision of PT glands.
Q. what’s the danger of HypoCa (from blood results)?
Tetany from HypoCa (extensive spasm of skeletal ms) can lead to laryngospasm and airway obstruction
Q. what clinical tests or signs are useful in asserting severity of HypoCa?
Chevostek sign cause contraction of ipsilat. facial muscles by taping on facial N. at the angel of the jaw
Trousseau sign spasm of the ms of UL to produce flexion of the wrist and thumb with extension of fingers which produced by occlusion of circulation by inflating a cuff above the SBP
Q. How to manage this pt with HypoCa ?
–Immediate IV accessa and IV CaGluconate 10 ml of 10% over 10min
–Freq. clinical obervations including monitoring of symptoms like parathesia or spasms and
–frq. Ca levels measurements and
–ECG monitoring (looking of T inversion and Prolonget QT)
Q1: How to calculate the corrected calcium?
Corrected calcium (mg/dL) = measured total Ca (mg/dL) + 0.8 (4.0 - serum albumin [g/dL]
