Sodium, urine
(Urine Na+)

Sample type

24-hour urine

Random urine

Uses

-Volume depletion: to determine the route of sodium loss. Low urinary sodium indicate extrarenal loss, and high value indicates renal salt wasting or adrenal insufficiency.

-Differential diagnosis of acute renal failure: high values are consistent with acute tubular necrosis.

-In hyponatremia, low urinary sodium indicates avid renal sodium retention, which may be attributable to either severe volume depletion or sodium-retaining states seen in cirrhosis,the nephrotic syndrome, and CHF. When hyponatremia is associated with urinary sodium excretion that equals or exceeds the dietary sodium intake, it is likely that SIADH is present.

Precautions

No specific needed but if the sample is 24-hour urine the sample should be collected with especial instructions.

24-hour urine sample collection instructions

• On day 1, urinate into the toilet when you get up in the morning.

• Afterward, collect all urine in a special container for the next 24 hours.

• On day 2, urinate into the container when you get up in the morning.

• Cap the container. Keep it in the refrigerator or a cool place during the collection period.

• Label the container with your name, the date, the time of completion, and return it as instructed.

Interfering factors

-Large diurnal variations exist in urine sodium levels.

-Levels are highly dependent on dietary intake and state of hydration.

-The rate of excretion during night is one fifth of the peak rate during the day

Pre-analytical errors

Unlanbeled sample

The corrective actions

The sample should be rejected and another sample requested

Post-analytical errors

1-Writing a wrong result or wrong name in the report

2-report were sent to incorrect patient

3-If the patient’s gender is written wrong in the report, the reference range was written incorrectly.

The corrective actions

1- If the report is not delivered to the patient and this error is discovered, the correct result or the correct name must be written, but if the report is delivered to the patient, you must communicate with the patient, apologise to him, and tell him that an error has occurred and replace it with the correct report.

2-Communicate with patient ,apologizing for the error, and providing him with the correct report.

3-If the report is not delivered to the patient and this error is discovered, fix it, but if the report is delivered to the patient, apologise to him, tell him that an error has occurred, and replace it with the correct report. And next time, Be careful when you write down the gender and reference range.

Reference range

24–hour urine:

Male:

Less than 10 years: 41–115 mmol/day

10–14 years: 63–177 mmol/day

Greater than 14 years: 40–120 mmol/day

Female:

Less than 10 years: 20–69 mmol/day

10–14 years: 48–168 mmol/day

Greater than 14 years: 27–287 mmol/day

Random urine

Male: 23–229 mmol/g creatinine

Female: 26–297 mmol/g creatinine