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MINERALS �PHOSPHORUS

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Dr. Ashish Agravatt ,

MBBS, MD.

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PHOSPHORUS

Sources

RDA

Metabolism

Functions

Disorders

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PHOSPHORUS - SOURCES

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PHOSPHORUS - RDA

800mg/day

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PHOSPHORUS-METABOLISM

Absorption

Factors affecting absorption

Excretion

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PHOSPHORUS-ABSORPTION

Site

Efficiency

Upper small intestine

70% absorbed

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FACTORS AFFECTING PHOSPHORUS ABSORPTION

Phosphorus absorption increased by

    • Bile salts
    • Acidity
    • PTH and vitamin D
    • Calcium

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Phosphorus absorption decreased by

    • High Ca: P ratio
    • Phytates
    • Alkalinity
    • Magnesium and aluminium

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PHOSPHORUS-EXCRETION

Urine

2/3 of ingested phosphate

0.6gm/day

Stool

Due to non-absorption

0.2 – 0.5 gm/day

Factors affecting renal excretion

↑ PTH

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PHOSPHORUS

FUNCTIONS

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Formation of bone and teeth

Production of high energy compounds

DNA and RNA synthesis

Synthesis of coenzymes

Synthesis of phosphoproteins and phospholipids

Activation of enzymes by phosphorylation

Acid base balance

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POSPHORUS - DISTRIBUTION

Human body contain about 840gm of phosphorus

80% present in bone and teeth

20% in other tissue

Plasma phosphorus : 3 – 4mg/100ml

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PLASMA PHOSPHORUS

    • ADULT
      • 3 -4mg/dl

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    • CHILDREN
      • 5 – 6mg/dl

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REGULATION OF PLASMA PHOSPHORUS

3 HORMONES

1,25(OH)2D3

PTH

Calcitonin

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REGULATION OF PLASMA PHOSPHORUS

1,25(OH)2D3

    • Increases absorption from intestine

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    • Increases the mobilization from bone

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    • Increases the renal reabsorption

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Increases plasma phosphorus

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REGULATION OF PLASMA PHOSPHORUS

PTH

    • Decreases the renal reabsorption

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Decreases plasma phosphorus

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REGULATION OF PLASMA PHOSPHORUS

Calcitonin

Inhibits bone resorption

Decreases the renal reabsorption

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Decreases plasma phosphorus

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DISORDERS OF PHOSPHORUS METABOLISM

Hypophosphatemia

Hyperphosphatemia

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HYPOPHOSPHATEMIA

Causes

Features

Treatment

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HYPOPHOSPHATEMIA - CAUSES

Decreased intake

Decreased absorption

Increased loss

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HYPOPHOSPHATEMIA - FEATURES

    • Hemolytic anemia
    • Leukocyte dysfunction
    • Platelet dysfunction

Acute

    • Anorexia
    • Weakness
    • Pain in the muscle and bones
    • Fractures

Chronic

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HYPOPHOSPHATEMIA - TREATMENT

Management of underlying disease

Administration of phosphate

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HYPERPHOSPHATEMIA

Causes

Featurs

Treatment

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HYPERPHOSPHATEMIA

CAUSES

Increased intestinal absorption

Decreased renal excretion

Extracellular shift of phosphorus

Hemolysis

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HYPERPHOSPHATEMIA FEATURES

Features of underlying diseases

Soft tissue calcification

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HYPERPHOSPHATEMIA TREATMENT

Treatment of underlying disorders

Dialysis in renal failure

Administration of aluminum hydroxide

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