Evaluation of Hyponatremia
The diagnostic workup should include a history and physical examination with specific attention to cardiac, cancer, pulmonary, surgical, endocrine, gastrointestinal, neurologic, and renal histories (Table 1).
Beside above, can low sodium be a lab error?
Pseudohyponatremia is an uncommonly encountered laboratory abnormality defined by a serum sodium concentration of less than 135 mEq/L in the setting of a normal serum osmolality (280 to 300 mOsm/kg).
Similarly, how can you tell the difference between true and pseudo hyponatremia?
How do you investigate hyponatremia?
Overall, serum osmolality and urinary sodium measurements are integral to the diagnosis and management of hyponatremia. Also required are clinical assessment and additional laboratory investigations that may include measuring urine osmolality, serum aldosterone, cortisol, and natriuretic peptide levels.
How do you read hyponatremia labs?
A urine osmolality value of less than 100 mOsm/kg indicates complete and appropriate suppression of antidiuretic hormone secretion. A urine sodium level less than 20 mmol/L is indicative of hypovolemia, whereas a level greater than 40 mmol/L is suggestive of the syndrome of inappropriate antidiuretic hormone secretion.
How is true hyponatremia diagnosed?
In health, sodium concentration is maintained between 135 and 145 mmol/L, so that hyponatremia (reduction in plasma sodium) is diagnosed if the concentration falls below 135 mmol/L.
Is potassium high or low in SIADH?
In SIADH, the urine sodium concentration is usually above 40 mEq/L, the serum potassium concentration is normal, there is no acid-base disturbance, and the serum uric acid concentration is frequently low [1].
What are 3 types of hyponatremia?
Hypovolemic hyponatremia: decrease in total body water with greater decrease in total body sodium. Euvolemic hyponatremia: normal body sodium with increase in total body water. Hypervolemic hyponatremia: increase in total body sodium with greater increase in total body water.
What is osmolality lab test?
Osmolality is a test that measures the concentration of all chemical particles found in the fluid part of blood. Osmolality can also be measured with a urine test. Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand.
What lab findings would you expect to see with SIADH?
Laboratory findings in patients with SIADH may show hyponatremia (sodium <135 mEq/L) and low serum osmolality (< 280 mOsm/kg). Patients with SIADH have elevated urinary sodium level (> 20 mMol/L) and urine osmolality (generally > 100 mOsm/L).
What labs do you order for hyponatremia?
There are three essential laboratory tests in the evaluation of patients with hyponatremia that, together with the history and the physical examination, help to establish the primary underlying etiologic mechanism: urine osmolality, serum osmolality, and urinary sodium concentration.