Urine Analysis: Part 25 – Phosphorus (Phosphates), 24 hours Urine sample
- The test sample is urine.
- Collect urine for 24 hours.
- Procedure to collect the 24 hours urine sample:
- Note down the time and empty the urinary bladder.
- Now collect all the urine samples till the 24 hours are completed.
- Empty the urinary bladder when the time is finished.
- Acidify the urine with acid. Add HCL.
- Acidify with HCL, and If pH <3 then urine is stable for 6 months.
- Vial should be washed with acid.
- Containers should be detergent free.
- Instruct the patient to void the first sample and note the time.
- After that, collect all the samples until 24 hours are completed.
- Now void the last sample in the container.
- Refrigerate the urine sample during collection.
- It helps in finding kidney problems.
- It helps to find the causes of kidney stones.
- Phosphorus levels will give an idea about renal or bone disease.
- Phosphorus in the body is in the form of phosphate, so phosphorus and phosphate are used interchangeably.
- The urine phosphate test measures the amount of mineral phosphate in the urine sample collected over a 24 hours period.
- The body needs phosphate :
- To build and repair the bones and teeth.
- To help nerves function.
- To help in muscle contraction.
- 85% of the phosphate is in the bones.
- The kidneys help and control the amount of phosphate in the blood.
- The extra amount of phosphate is excreted by the kidneys in urine.
- Phosphate is a charged particle (ion) that contains the mineral phosphorus.
- The extra phosphate is filtered by the kidneys and passes out of the body in the urine.
- Kidney diseases can affect the phosphate level in the urine.
- If the blood has less phosphate, then it is less in the urine.
- Eating a meal high in phosphorus will increase the phosphate level.
- High levels of vitamin D and overactive parathyroid gland increase the phosphorus level.
Phosphorus, inorganic in the urine:
- Constant daily diet = <1.0 g/day (<32.3 mmol/day).
- Nonrestricted diet = 0.4 to 1.31 g/day (12.9 to 42.0 mmol/day).
- Constant daily diet = 0.9 to 1.5 g (29 to 48 mmol)phosphorus and calcium 10 mg/kg (0.25 mmol/Kg)
- Adult = 0.4 to 1.3 grams / 24 hour urine sample.
- Calcium- and phosphate-restricted diet = < 1.0 g per 24 hour urine sample.
Raised urine phosphate is seen in:
- Kidney diseases.
- Excessive intake of vitamin D.
Decreased phosphate level in the blood is seen in:
- When the level is <2.5 mg/dL in the blood.
- Kidney diseases.
- Liver diseases.
- Severe malnutrition.
- In hospitalized patients.
Normal urine picture:
Physical features Chemical features Microscopic findings
- Color = Pale yellow or amber
- Appearance = Clear to slightly hazy
- pH = 4.5 to 8.0
- Specific gravity = 1.015 to 1.025
- Blood = Negative
- Glucose = Negative
- Ketones= Negative
- Protein = Negative
- Bilirubin = Negative
- Urobilinogen = Negative (±)
- Leucocyte esterase = Negative
- Nitrite for bacteria = Negative
- RBCs = Rare or Negative
- WBC = Rare or Negative
- Epithelial cells = Few
- Cast = Negative (Occasional hyaline)
- Crystal = Negative (Depends upon the pH of the urine)
- Bacteria = Negative