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Test Name:
Phosphorus, Urine, 24-Hour
- SBMF No:
23308 - Performance Lab Name:
Automated Lab - Test Mnemonic:
U PHOS24 - ABN:
Not required - CPT Code:
84105 - LOINC Code:
2779-7; 20624-3; 2162-6; 13362-9; 3167-4; 19150-2; 21458-5 - Test Includes:
Phosphorus
Creatinine - Also Known As:
PO4 - Spec Type:
Urine, 24-hour - Spec Container:
Plastic container with tightly fitting lid (no preservative) - Pref Vol:
20.0 mL aliquot from well-mixed 24-hour collection
Note: Send urine aliquot with notation of entire 24-hour urine volume on aliquot label and on requisition - Min Vol:
10.0 mL aliquot from well-mixed 24-hour collection - Fasting:
No - Spec Collect:
To begin collection of timed specimen, have patient urinate, noting date and exact time
Discard this first portion of urine, but document date and time of voiding on container label and test requisition as "start" of timed specimen
Save all urine voided during designated time period, including portion voided at exact end of time period
IMPORTANT: Refrigerate entire specimen (2-8°C) during and after collection to prevent bacterial growth
Document date and time of final voiding on label and requisition as "end" of timed specimen - Spec Process:
Upon completion of the collection, mix the entire specimen very well, and measure the 24-hour volume
Pour off 20.0 mL of urine into separate plastic tube(s)
Refrigerate urine aliquot and transport refrigerated
Send urine aliquot with notation of entire 24-hour urine volume on aliquot label and on requisition - Spec Store Transport:
Refrigerated - Spec Stability:
1 week refrigerated (2-8°C)
Greater than 1 week, freeze (-20°C) – Do not use frost-free units that undergo repeated freeze/thaw cycles - Methodology:
Photometric - Use:
Evaluate calcium/phosphorus balance
Evaluate nephrolithiasis - Clinical Significance:
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. - Reference Range:
0.4-1.3 g/24 hours, diet dependent - Critical High Value:
25.0 g/24 hours - Additional Test Info:
Record total specimen volume, collection times, and pH [if required] on test requisition - Day Run:
Sun-Sat (daily) - Time Run:
As received - Time Reported:
4 hours - Test Type:
URINE
