Phosphorous, Urine, 24 hour

Phosphorus, Urine, 24-Hour

Alternate Test Name

Urine Phosphorus 24 hour, PO4

Epic Mnemonic
Sunquest Mnemonic

LAB426
PHOSUB

Category

Sendouts

Methodology

Photometric

Test Performance Schedule

Sunday - Saturday

Result Availability

1 – 4 days

Container

24-hour Urine Container, no preservative

Volume

Entire timed urine

Collection Instructions

• To begin collection of timed specimen, have patient urinate, noting the date and exact time
• Discard this first portion of urine, but document date and time of voiding on the container label and test requisition as the "start" of the timed specimen
• Save all urine voided during the designated time period (usually 24 hours), including the portion voided at exact end of time period
• Document date and time of final voiding on the label and requisition as the "end" of the timed specimen

24 Hour Urine Collection Instructions

Transportation Instructions

Refrigerate during and after collection

• Upon receipt in the laboratory, mix entire specimen well and note 24-hour volume
• Aliquot 20 mL urine into a screw-capped plastic transport tube
• Refrigerate urine aliquot and transport refrigerated

Stability

Room temperature: Unacceptable
Refrigerated: 1 week
Frozen: Greater than 1 week (avoid repeat freeze/thaw cycles)

Causes for Rejection

Specimens collected in metal containers.

CPT Codes

84105

Effective/Revised

7/12/18

Eighty eight percent of the phosphorus contained in the body is localized in bone in the form of calcium phosphate as the apatite Ca2+[Ca3(PO4)2]3 2-. The remainder is involved in intermediary carbohydrate metabolism and in physiologically important substances such as phospholipids, nucleic acids and ATP. Phosphorus occurs in blood in the form of inorganic phosphate and in organically bound phosphoric acid. The small amount of extracellular organic phosphorus is found almost exclusively in the form of phospholipids. The ratio of phosphate to calcium in the blood is approximately 6:10. An increase in the level of phosphorus causes a decrease in the calcium level. The mechanism is influenced by interactions between parathormone and vitamin D. Hypoparathyroidism, vitamin D intoxication and renal failure with decreased glomerular phosphate filtration give rise to hyperphosphatemia. Hypophosphatemia occurs in rickets, hyperparathyroidism and Fanconi’s syndrome.