Internal Medicine

0521779407-17 CUNY1086/Karliner 0 521 77940 7 June 13, 2007 7:57

Phosphate Deficiency 1171

PHOSPHATE DEFICIENCY

ELISABETH RYZEN, MD

history and physical

History:

alcoholism, diabetic ketoacidosis, severe burns, TPN, malnutrition,

hyperparathyroidism, Vitamin D deficiency, malabsorption syndrome,

hypomagnesemia, chronic ingestion of phosphate-binding antacids,

refeeding (transcellular shifts)

Physical:

muscle weakness (including respiratory muscles), anorexia, rhabdomy-

olysis, impaired cardiac output, osteomalacia (chronic), hemolytic ane-

mia, impaired leukocyte and platelet function

tests

Laboratory

■Basic studies: blood (serum phosphate <2.5 mg/dL)

■Severe symptoms (e.g., hemolytic anemia, impaired cardiac output)

only develop with phosphate <1 mg/dL)

■DDx N/A

management

What to Do First

■Assess severity of symptoms (respiratory, cardiac)

General Measures

■Treat underlying cause, feed patient phosphate-rich foods if possible

(e.g., skim milk)

specific therapy

■oral replacement with sodium or potassium phosphate (e.g., Neutra-

Phos 500 mg p.o. qid) – may cause diarrhea

■IV for severe hypophosphatemia and symptoms (assess renal func-

tion first):

➣e.g., 2–5 mg/kg IV phosphate as K-phosphate slowly over 6–8 h

Contraindications to Treatment

■Absolute

➣Elevated serum phosphate level; inability to accurately control

amount of phosphate given

■Relative

➣Renal failure – use with extreme caution even if mild creatinine

elevations, lower doses