Calcium metabolism and its clinical significance can be summarized as follows:
(1) Calcium is primarily stored in bones and is important for bone formation and health. It is also present in extracellular fluid and involved in many metabolic processes.
(2) Calcium absorption occurs primarily in the duodenum and is regulated by factors like vitamin D, parathyroid hormone, acidity, and certain amino acids.
(3) Calcium levels in the blood are tightly regulated by hormones including PTH, calcitonin, and vitamin D which act on bones, kidneys, and intestines to influence calcium absorption, reabsorption, and mobilization from bones.
(4) Disorders of calcium
52. Factors regulating blood calcium levels
V SERUM PROTEIN :
Nephritis ,malnutrition à Hypo-albuminemia à serum calcium decreases
Decrease in Albumin by 1 g à decrease in serum calcium by 0.8 mg/ dl (
calcium bound to Albumin )
Metabolic active :ionized form is normal. Therefore no deficiency manifestation.
VI Alkalosis & Acidosis :
Alkalosis à favors Calcium + protein : decrease ionized form
Acidosis àFavors ionization of Calcium
VII Kidney Threshold :
Kidney threshold : 10mg/dl
Calcium intravenous injection à urinary excretion
Calcium ( Ca ²⁺) ,Magnesium ( Mg ²⁺) , proton ( H ⁺) prevents tetany .
58. Hyper parathyroidism
MAJOR CAUSE of Hypercalcemia : > 11mg/ dl ( Normal serum Calcium: 9-11 mg/dl )
Causes :
a) Parathyroid –Adenoma
b) Ectopic secreting tumors
Signs & Symptoms :
1. Osteoporosis
2. Punch out areas of bone reabsorption
3. Calcium excretion in urine ( Calciuria )
4. Calcium precipitate in urine à urinary calculi
5. Retention of chloride à Hyper chloremic acidosis à polyuria ( increased solutes
in urine )
6. Anorxia ,mucle weakness ,short Q-T interval in in ECG
7. Ectopic calcium in eal tissue , pancreas ,arterial wall ,muscle tissue ,ossificans )
62. Tetany-1
q Causes of Tetany :
1. Decrease in Dietary intake
2. Surgical removal of parathyroid gland
3. Auto immune disease
qSigns & symptoms :
a) Neuro- muscular irritability
b) Carp pedal spasm
c) Laryngismus à DEATH
d) Chvostek’ s sign à tapping of 5th cranial nerve ,facial contraction
e) Trousseau’s sign à inflammation of blood pressure causes carpopedal
spasm
f) Increases Q-T interval in ECG
78. Osteoporosis
a) Age30 years àMaximum calcium content in bone
b) Age 45-50 years à Calcium absorption decreases ,calcium excretion
increases ( negative balance )à demineralization ( OSTEOPENIA )
c) Age 60 years à
Absorption of vitamin D ↓
Androgen & Estrogen ↓
Serum Calcium ↓
Reduced bone stregth
Repeated bone fractures à OSTEOPOROSIS
OSTEOPOROSIS : WOMEN > MEN , INDIANS > WESTERNERS