8. Calcium absorption is increased by
Calcitriol
PTH
High protein diet
Optimum Ca:P ratio
Acidic pH
Bile salts
Absorption is decreased by
Alkaline pH
Phytates and oxalates
Steatorrhea
Vitamin D deficiency
Excess phosphate in diet
11. Human body
contain
about 1-1.5
kg of calcium
99% present in bone
and teeth
1% in soft tissue and
extracellular fluid
Plasma calcium : 9-11mg/100ml
Ionized calcium: 4.65-5.25mg/100ml
12. Formation of
bone and teeth
Nerve
conduction
Muscle
contraction
Activation
of enzymes
Blood coagulation
Secretion of
hormones
As a second
messenger
Action on
myocardium
20. Causes of hypocalcemia
I. Factitious hypocalcemia:
Is the reduction of the total , not the ionized fraction of
serum calcium with reduction of serum albumin, the
patient don't have any symptoms or signs of
hypocalcaemia
If the serum albumin levels fall to < 4 g/dl., the usual
correction is to add 0.8 mg/dl to the measured total serum
calcium for every 1.0 gm/dl reduction of serum albumin.
21. II. Hypoparathyroidism
Hypoparathyroidism is the state of decreased secretion
or decreased activity of PTH
Manifestations that occur result from associated
hypocalcemia and hyperphosphatemia.
22. Three categories of hypoparathyroidism
Deficient PTH secretion
(> 99% of all cases
In ability to make an
active form of PTH care.
Inability of kidneys and bones
to respond to parathyroid hormone
being produced by normal parathyroid .
23. III. Magnesium depletion and hypocalcemia:
Normal mg serum level is 1.6-2.1 mEq/L
Mg metabolism has a close association with that of
calcium:
Are competitive for renal tubular reabsorption
Are physiological antagonists in CNS
Mg is necessary for PTH release and for its action
Patients with hypocalcemia due to Mg deficiency should be
treated with IV mg at a dose of 48 mEq over 24 hours.
24. IV. Hypocalcemia and hyper phosphatemia:
85% is free and only 15% is protein bound
Hypocalcemia and tetany may occur if serum
phosphorus rises rapidly
Hyperphosphatemia alters calcium and phosphate
ion solubility products, and calcium deposition in
soft tissue may occur.
25. V. Medications and toxins causing
hypocalcemia:
Mithramycin, bisphosphonates, calcitionin, oral or
parentral phosphate preparation, anticonvulsants manly
(phenytoin or phenobarbital)
Plasmapheresis with citrated blood
Radiographic contrast dyes
Chemotherapeutic agents.
During surgical procedures, hypocalcemia may occur in
the absence of citrated bl. Infusion, may be due to acute
hemodilution by physiological saline.
27. IX.Vitamin D disorders resulting in hypocalcemia:
Both inherited and aquired disorders of vit D and its metabolites may be
associated with hypocalcemic disorder.
Decreased synthesis of vit D3 in the skin may be due to lack of sun
exposure
Fat malabsorption
Extensive liver disease
Drugs, mainly anticonvulsant.
Nephrotic syndrome, may be due to excretion of vit D binding protein.
Ch. R.F. with reduction of GFR to <30% may present with production of
1-25 dihydroxy vit D.
29. Contraction of facial muscle in response to tapping
the facial nerve, (insensitive test)
Chvostek’s
sign
Carpal spasm occurring after occlusion of the
brachial artery with BP cuff with pressure 20 mm
of Hg above systolic BP for 3-5min.
Trousseau’s
sign
33. Management
1. Dependent on the underlying cause and severity
2. Administration of calcium alone is only
transiently effective
3. Mild asymptomatic cases: Often adequate to
increase dietary calcium by 1000 mg/day
4. Symptomatic: Treat immediately
34. Investigations
• Serum calcium
• Ionic calcium
• Serum magnesium
• Blood urea
• Serum creatinine
• Serum amylase & serum lipase
• Serum proteins;- total proteins,albumin,globulin
• Serum electrolytes
• PTH hormone immunoassay.
• Tests for vitamin D metabolites.
• Measurements of the urinary cyclic AMP response to exogenous PTH.
• 25(OH)D assays.
36. Rx for factitious hypocalcemia
• Low serum albumin levels can cause a reduction
in the total, but not the ionized ,fraction of serum
calcium.
• Each 1g/dL reduction in the serum albumin
concentration will lower the total calcium
concentration by approximately 0.8mg/dL
without affecting the ionized calcium
concentration.
37. -:Formula:-
• Thus ,calcium level should be corrected in patients with low
serum albumin levels ,using the formula :
• Corrected calcium(mg/dL)= measured total
Ca(mg/dL)+0.8(4.0-serum albumin <g/dL>),
• Where 4 respresents the average albumin
level.
38. i. Acute hypocalcaemia:
Calcium gluconate is the preferred IV calcium.
Calcium gluconate contains 90 mg of elemental calcium/ 10 ml
ampoule.
Usually 1-2 ampoule (180 mg of elemental calcium) diluted in 50-
100 ml of 5% dextrose, is infused over 10 minutes. This can be
repeated until the patient's symptoms have cleared. The goals
should be to raise serum calcium by 2-3 mg/dl with the
administration of 15mg/kg of elemental calcium over 4-6 hours.
Calcium should be maintained in the low normal range. If possible
oral calcium supplementation should be initiated together with vit
D.
39.
40. ii- Chronic hypocalcemia
• Patients who are asymptomatic or with mild symptomatic
hypocalcaemia can be treated with oral calcium and vit D.
• The overall goal of therapy is to maintain serum calcium in the
low normal, range, serum calcium should be tested every 3-6
months.
41. Hypocalcemia with concurrent hypomagnesemia
• Often cannot correct the Ca unless the Mg is corrected
• Give 2 gm of Mg (16 meq) of MgSO4 as a 10% solution over 10
to 20 minutes
• Followed by 1 gm MgSO4 (8 meq) at 100 mL/hr
• Continue intravenous MgSO4 as long as Mg < 1 mg/dL
• Careful monitoring if patient has impaired renal function
42. Calcium salts
Drug preparation: Ca= elemental calcium
• Calcium chloride (27.2% cal) 10% solution (100 mg/ml)
given IV but cause local irritation.
• Calcium gluconate.
• Calcium carbonate: 40% calcium e.g oscal, titralac.
• Calcium citrate 21% cal (citracal).
• Calcium lacate 13% calcium.
43. Vit D preparation:
Ergocalciferol: (calciferol)
Calcifediol (25-hydoxy vit. )
Calcitriol: (1,25 dihydroxy vit D )
44. Vitamin D dosage in Rx of chronic hypocalcemia
Simple dietary deficiency - can be corrected by the use of ergocalciferol
400-2000 IU/day
• However in conjunction with other hypocalcemic disorders (e.g.,
underlying impairments in vitamin D metabolism or renal insufficiency)
larger doses may be needed e.g., a 6 to 8 week regimen of 50,000
units, dosed weekly
• Severe malnutrition or malabsorption – may require even higher doses