Ortho-Preferred

HypoPhosphatemia: diff dx



- Discussion:
    - normal phosphate serum levels are 3 to 4.5 mg/dL in adults and 4 to 7.5 mg/dL in children (Boyd & Olin, 1984);
           - hypophosphatemia occurs with serum P levels of < 0.8 mmol/L (2.5 mg/dL);

- Differential Dx:
    - rickets / osteomalacia:
           - hypophosphatemia is the most common metabolic anomaly in rickets;
           - hypophosphatemic vitamin D-resistant rickets:
    - hyperparathyroidism
    - ETOH
    - diabetes mellitus
    - hyperalimentation
    - acidosis,
    - alkalosis
    - gout
    - salicylate poisening
    - steroids
    - glucose and/or Insulin administration
    - hypokalemia
    - hypomagnesemia
    - diuretics
    - vitamin D defficiency
    - phosphate binding antacids
    - malabsorption;

- Clinical Manifestations:
    - acute manifestations of phosphorous deficiency include central nervous system dysfunction (lethargy, altered mental status, focal  neurological findings), muscular weakness and rhabdomyolysis, hemolytic anemia, & defects in platlet and leukocyte function;
    - metastatic calcification can occur if the calcium-phosphorus product exceeds 2.5 x 10(-6) mmol/L (5.8 mg/dL);
         rickets, multiple sclerosis, and diabetic ketoacidosis;

- Dosing Information:
    - severe hypophosphatemia may require 300 mg phosphorus IV in half-normal saline infused over 12 hours.
    - K-phos neutral - phosphorus 250 mg, sodium 298 mg, potassium 45 mg;
    - Neutra-phos - phosphorus 250 mg, sodium 164 mg, potassium 278 mg;
    - Neutra-phos-k - phosphorus 250 mg, potassium 556 mg;
    - Dietary supplement;
         - recommended daily allowance of phosphorus is 1200 milligrams daily in males and females 11 to 18 years of age;
         - allowance is 800 milligrams daily in males and females 19 years of age and older;
    - 1-2 grams of oral phosphorus/day are effective in treating adult hypercalcemia;
    - 1.5 g IV infused over 6 to 8 hours may be used in severe, life-threatening hypercalcemia.
    - to treat hypophosphatemia, 1 to 3 g oral or rectal phosphorus may be given daily to adults; children should receive 1 to 2 mmol/kg/24 hours IV or 2 to 4 mmol/kg/24 hours PO



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, September 5, 2012 8:29 pm