1. Calcium & phosphorus

2. Calcium Physiology Distribution
Fifth element, main cation, kg, 99%, 1%, 1%.
Forms (plasma)
Free,50%
Complexed with anions,10%
Protein-bound,40%
Albumin,80%
binding is pH dependent.
plasma protein concentration

3. Calcium Function Skeletal mineralization,Ca5(PO4)3(OH)
Blood coagulation,
Neural transmission,
Plasma buffering capacity,
Enzyme activity,
Maintenance of normal muscle tone
Excitability of skeletal & Cardiac muscle

4. Recommended adults daily intake Absorption
1200 mg
Absorption
Duodenum & upper jejunum
Less than half
Increases
rapid growth in children, in pregnancy, and during lactation.
Vitamin D
Decreases
Age, oxalate and fatty acids, The ratio (Ca/P)

5. Excretion Sweat (15-100 mg/day) Urinary (100-200 mg/day) Enhanced
hypercalcemia,phosphate deprivation, acidosis, and glucocorticoids.
Diminished
Parathyroid hormone (PTH), certain diuretics, and probably vitamin D

6. Calcium Homeostasis Ionized calcium of the ECF
Concentration μmol/L
Adjustment
PTH & active 1,25(OH)2D3), calcitonin
Organs
bone, kidney, and intestine.
Thyroid hormone, growth hormone,adrenal glucocorticoids, and gonadal steroids.

8. Analytical Techniques
Colorimetric analysis with metallochromic indicators
atomic absorption spectrometry
(AAS)
Indirect potentiometry

10. Reference Interval total calcium in normal adults SAMPLE Interference
mg/dL ( mmol/L).
SAMPLE
Serum
Heparinized plasma
Interference
Citrate, oxalate, and ethylenediaminetetraacetic acid (EDTA)
Hemolysis, icterus, lipemia, paraproteins, & magnesium.

11. Ionized (free) calcium Proper collection
mg/dL ( mmol/L).
Proper collection
Specimens should be collected anaerobically
on ice
Glycolysis
Urinary calcium varies with diet
up to 300 mg/day
Acidification

12. Phosphorus,Physiology
Distribution
Skeleton, 80-85%
Hydroxyapatite and calcIum phosphate
ECF, soft tissues: 15%
inorganic phosphate
Organic phosphates
Two thirds of blood phosphorus is organic,
Inorganic
3-4 mg/dL of the total of 12 mg/dL
Divalent (HPO42-) and monovalent (H2PO4-)
The ratio is pH dependent

13. Phosphorus Physiology
10%
bound to proteins
35%
Complexed with sodium, calcium, & magnesium
55%
Free
Only inorganic phosphorus is measured in routine clinical settings

14. Phosphorus Function Skeleton Intracellular Extracellular Phospholipids
nudeic acids
Extracellular
Phospholipids
Phosphoproteins
high-energy compounds
Cofactors
intermediary metabolism
Oxygen carrying (2,3-DPG)

15. Phosphorus Homeostasis
Blood phosphate
Most, Diet
dairy products, cereals, eggs, and meat
60-80% is absorbed
Passive (mainly) & active (1.25(OH)2D3) transport.
Some from bone
Kidney
80%, reabsorbed in the proximal tubule
Na-P cotransport
Intake and PTH regulate
Small, distal tubule

16. Phosphorus Homeostasis
Serum phosphate
PTH lowers
Vitamin D
Intestinal absorption and renal reabsorption
Growth hormone.
Reduces renal excretion

17. Analytical Techniques
Inorganic phosphate
reaction of phosphate with ammonium molybdate
phospho molybdate complex
absorption at 340 nm
or phospho molybdate complex reduced
Molybdenum blue nm
pH dependent, protein concentration
enzymatic method

18. Analytical Techniques
Glycogen phosphorylase, phosphoglucomutase, glucose-6-phosphate dehydrogenase (G6PD)
NADPH quantitated spectrophotometrically.
Sample
Serum is preferred
elevated levels
Prolonged storage RoomT
Hemolyzed

19. Reference Interval Normal adult Specimens Influenced by
mg/dL ( mmoI/L).
Specimens
Fasting morning
Influenced by
dietary intake, meals, and exercise.
Age
Growing children, Higher levels