Urine Analysis: Part 15 – Urine Sodium (Na+), Spot test, or 24 Hours Urine Sodium
- Can collect the random sample.
- Collect 24 hours urine sample.
- Urine container should be refrigerated or put on the ice.
- Discard the first sample and collect all other samples for 24 hours.
- Add the last sample to the container.
- During collection, refrigerate the samples.
- Dietary intake of sodium salt increases the sodium level.
- Drugs like antidiuretics increases are antibiotics, steroids, laxatives, and cough medicines.
- Drugs that may decrease sodium levels are diuretics (furosemide, Lasix) and steroids.
- The increased level may be seen after caffeine, diuretics, dehydration, dopamine, and postmenstrual diuresis increased sodium intake and vomiting.
- The decreased sodium level is associated with corticosteroids, and propanolol, in over-hydration and stress diuresis.
- This test evaluates fluid and electrolytes abnormalities (acid-base balance).
- It is done to monitor the treatment.
- Advice for diagnosing adrenal diseases.
- Advice for the diagnosis of renal diseases.
- Sodium is the primary regulator for retaining or excreting the water and regulating the acid-base balance.
- Sodium is a major cation of the extracellular fluid.
- Sodium has the ability to maintain the acid-base balance by combining with chloride and bicarbonate.
- It helps in neuromuscular function.
- Sodium is responsible for almost 50% of the osmotic strength of the plasma.
- It helps to maintain the osmotic pressure of the extracellular fluid.
- The daily diet contains 8 to 15 grams (130 to 260mmol) per day.
- Body requirement is only 1 to 2 mmol, and excess is excreted in the urine by the kidney.
- Aldosterone stimulates kidneys, decreases renal losses, and increases reabsorption.
- ADH control reabsorption of water at distal tubules affects Na+ level by dilution of urine.
- Na+ promotes normal electrolyte balance in the Intracellular and extracellular fluids in the association of K+ under the Aldosterone hormone’s influence.
- This hormone promotes the 1:1 exchange of sodium for potassium or hydrogen ions.
- A natriuretic hormone produced in response to increase Na+ decreases reabsorption and increase Na+ losses.
- Sodium transport is an active process.
- In hyponatremia, when blood Na+ level is low, if it is due to inadequate intake, urine Na+ will also be low.
- In renal dysfunction, like a chronic renal failure, urine Na+ will be high, and serum Na+ will be low.
- Maintenance of the normal urine Na+ depends upon:
- Dietary intake.
- .The kidney’s ability to excrete the Na+.
- Effect of the aldosterone produced by the adrenal glands.
- It causes increased reabsorption of the Na+ in distal tubules and leads to a lower level in urine Na+.
- The posterior pituitary gland secretes the antidiuretic hormone.
- ADH controls the reabsorption of the water in the collecting ducts, causing its return to the bloodstream.
- It causes decreased water in the urine and an increase in the urine Na+.
- There is diurnal variation in the excretion of the Na+; this is more in the daytime than during the night.
The basis of the test:
- This test evaluates the Na+ balance in the body by determining 24 hours urinary Na+.
- Measurement of Na+ in urine gives information like :
- Acute renal failure.
- Adrenal disturbances.
- Acid-base balance.
- Evaluate patients with volume depletion.
- In acute renal failure:
- Raised Na+ level indicates Acute tubular necrosis.
- Low Na+ level indicate prerenal azotemia.
|6 to 10 years|
|Male||41 to 115|
|Female||20 to 69|
|10 to 14 years|
|Male||63 to 177|
|Female||48 to 168|
|Adult||40 to 220|
|27 to 287|
Conversion factor for SI unit = x 1.0 = mmol/day.
- 24 hours urinary sodium
- Adult = 40 to 220 meq/day (40 to 220 mmol/24 hours).
- Child = 41 to 115 meq/24 hours (41 to 115 mmol/day).
- Random urinary sodium = > 20 meq/L.
- Values are diet-dependent.
- 15 to 250 meq/L/day (15 to 250 mmol/L/day).
- It depends on hydration and the intake of dietary NA+.
Increase urine Sodium is seen in:
- Diuretic therapy.
- Adrenocortical deficiency.
- Diabetic Ketoacidosis.
- Chronic renal failure.
- Excessive use of Na+ in the diet.
- Toxemia of pregnancy.
- Syndrome of inappropriate ADH secretion.
Decreased urinary sodium is seen in:
- Congestive heart failure.
- Cushing’s syndrome.
- Aldosteronism (Hyperaldosteronism).
- Inadequate sodium intake.
- Renal diseases like kidney failure or chronic renal diseases.
- A liver disease like cirrhosis.
- Pulmonary emphysema.
- Inadequate intake of sodium.
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