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Phosphorus (PHOS1)

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EPIC Test Name

PHOSPHORUS LEVEL

EPIC Code

LAB113

Specimen Requirements

plasma
Minimum Volume:0.5 mL
Collection:Collect using standard laboratory procedures
Transport:Room Temperature ASAP
Stability:Room Temperature: 24 hours at 20-25 degrees C
Refrigerated: 4 days at 2-8 degrees C
Frozen: 1 year at -20 degrees C
Container:LIT GRN
Processing/Storage:Centrifuge, pour off, and refrigerate plasma.
Rejection Causes:Hemolysis,
Insufficient Sample Volume

Methods

Molybdate UV

Turnaround Time

SpecimenTurnaround TimeFrequency
plasmaStat: 90 minutes Routine: 4 hours24/7

Reference Ranges

Molybdate UV
AgeAll RangeUnitCritical Values
0 days up to 10 days4.5-9.0 mg/dLmg/dL
10 days up to 2 years4.5-6.7 mg/dL<28 days old: <3.5 and >10.0 mg/dL
2 years up to 11 years4.5-5.5 mg/dL
11 years up to 999 years2.5-4.5 mg/dL>28 days old: <0.9 mg/dL

Clinical Indications

Phosphorus exists in inorganic and organic forms. Inorganic phosphate is the form that is measured and is primarily contained in bone as hydroxyapatite. Most intracellular phosphate is organic and plays a significant role in gene transcription, cell growth, and protein, fat, and carbohydrate intermediary metabolism regulation. Phosphate regulation depends on 1,25(OH)2D, parathyroid hormone (PTH), and FGF23. 1,25(OH)2D promotes phosphate absorption in the intestines while PTH and FGF23 both promote renal clearance of phosphate, leading to reduced serum levels.
Hypophosphatemia can occur to patients with rickets, hyperparathyroidism and Fanconi's syndrome due to malnutrition, malabsorption, acid-base imbalances, increased blood calcium, and/or disorders that affect kidney function. Intracellular shifting primarily occurs as a result of carbohydrate-stimulated insulin release in the body. Renal wasting can result from hyperparathyroidism or renal tubular defects. Inadequate intestinal absorption can result from Vitamin D deficiency, chelation by antacids, or loss through diarrhea or vomiting. Intracellular stores of phosphate can be depleted as a result of acidosis or certain genetic conditions.
Hyperphosphatemia often arises as a result of poor renal excretion, especially in patients with renal failure. Lysis of cells shifts intracellular stores of phosphate extracellularly, raising serum phosphate concentrations. Acidosis, increased intake, and Vitamin D intoxication can also lead to hyperphosphatemia.

Additional Information

Serum phosphorus levels have a diurnal variation dependent on dietary intake. Levels are lowest in the morning, have a peak in the late afternoon, and have their highest levels in a second peak in the early morning.

Hemolyzed samples causes false elevation of phosphate concentrations.

Performed

Lab
Chemistry - Community
Chemistry - Downtown

Interpretative Information

Symptoms of hypophosphatemia usually manifest once plasma concentrations fall below 1.5 mg/dL and include muscle weakness, acute respiratory failure, and cardiac arrhythmias. Severe hypophosphatemia can lead to rhabdomyolysis, hemolysis, and altered mentation. Chronic hypophosphatemia causes poor bone development and impaired growth.
Symptoms of hyperphosphatemia depend on rate of onset. A rapid increase in phosphate levels causes hypocalcemia, leading to tetany, seizures, and hypotension. Chronic hyperphosphatemia can lead to secondary hyperparathyroidism, osteitis fibrosa, and soft tissue calcification.

CPT

84100

LOINC

2777-1

References

1. Delaney MP, Lamb EJ: Kidney disease. In: Rifai N, Horvath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:1280-1283
2. Agarwal R, Knochel JP: Hypophosphatemia and hyperphosphatemia. In: Brenner BM, ed. The Kidney. 6th ed. WB Saunders Company; 2000:1071-1125
3. Yu GC, Lee DBN: Clinical disorders of phosphorus metabolism. West J Med. 1987 Nov;147(5):569-576
4. Koumakis E, Cormier C, Roux C, Briot K: The causes of hypo- and hyperphosphatemia in humans. Calcif Tissue Int. 2021 Jan;108(1):41-73. doi: 10.1007/s00223-020-00664-9
5. “Test Id: Phos Phosphorus (Inorganic), Serum.” PHOS - Clinical: Phosphorus (Inorganic), Serum, Mayo Clinic Laboratories, www.mayocliniclabs.com/test-catalog/Clinical+and+Interpretive/8408.
6. Quarles LD. Role of FGF23 in vitamin D and phosphate metabolism: implications in chronic kidney disease. Exp Cell Res. 2012 May 15;318(9):1040-8. doi: 10.1016/j.yexcr.2012.02.027. Epub 2012 Mar 7. PMID: 22421513; PMCID: PMC3336874.

Contact Information

Chemistry - Downtown: (315)464-4460
Chemistry - Community: (315)492-5531
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