| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Osmolality, Urine
Test CodeOSMOU - NOCO
CPT Codes
83935
Preferred Specimen
5 mL 24 hour urine OR random urine
Note: If preferred specimen type is not noted, collect/order random urine.
Note: If preferred specimen type is not noted, collect/order random urine.
Minimum Volume
1.0 mL
Instructions
24 Hour Urine Collection Instructions English / Spanish
Random Urine Collection Instructions - English / Spanish
Random Urine Collection Instructions - English / Spanish
Specimen Stability
| Specimen Type | Temperature | Time |
| Urine | Refrigerated | 7 days |
Methodology
Freezing Point Depression
Setup Schedule
Monday through Sunday; Continuously
Report Available
Same day
Reference Range
NCMC & BFCMC
No established reference values
MMC
0-18 years: 50 - 1400 mosm/kg
18-150 years: 300 - 900 mosm/kg
No established reference values
MMC
0-18 years: 50 - 1400 mosm/kg
18-150 years: 300 - 900 mosm/kg
Clinical Significance
Osmolality is used to evaluate the concentrating ability of the tubules in the kidneys.
Low serum or plasma osmolality levels are seen in adrenocortical insufficiency, panhypopituitarism, water intoxication and
postoperative status, (especially with excessive water replacement therapy, syndrome of inappropriate ADH secretion).
High serum or plasma osmolality levels are seen with water depletion, hyper-osmolar, nonketotic diabetic coma, diabetic
ketoacidosis, hypernatremic ethanol intoxication, diabetes insipidus, hypercalcemia, cerebral lesions, and often with tube feeding.
Low urine osmolality levels are seen with diabetes insipidus and primary polydipsia. After fluid restriction of 12-14 hours, a patient
with normal renal function should be able to concentrate urine to at least 800 mOsm/kg. Loss of this function is seen in early renal
failure, and a concentration ability of only 400 mOsm/kg would indicate severe renal dysfunction.
The normal ratio of urine osmolality to serum osmolality is between 1.0 – 3.0. In patients with fluid restriction, the ratio is ≥3.0 and
may rise in extremes to 4.7. In renal tubular deficiency, the ratio is <3.0 and may rise in extremes to 4.7. In polyuria of diabetes
insipidus, the ratio will be 0.2 – 0.7.
Low serum or plasma osmolality levels are seen in adrenocortical insufficiency, panhypopituitarism, water intoxication and
postoperative status, (especially with excessive water replacement therapy, syndrome of inappropriate ADH secretion).
High serum or plasma osmolality levels are seen with water depletion, hyper-osmolar, nonketotic diabetic coma, diabetic
ketoacidosis, hypernatremic ethanol intoxication, diabetes insipidus, hypercalcemia, cerebral lesions, and often with tube feeding.
Low urine osmolality levels are seen with diabetes insipidus and primary polydipsia. After fluid restriction of 12-14 hours, a patient
with normal renal function should be able to concentrate urine to at least 800 mOsm/kg. Loss of this function is seen in early renal
failure, and a concentration ability of only 400 mOsm/kg would indicate severe renal dysfunction.
The normal ratio of urine osmolality to serum osmolality is between 1.0 – 3.0. In patients with fluid restriction, the ratio is ≥3.0 and
may rise in extremes to 4.7. In renal tubular deficiency, the ratio is <3.0 and may rise in extremes to 4.7. In polyuria of diabetes
insipidus, the ratio will be 0.2 – 0.7.
Performing Laboratory
Banner Fort Collins Medical Center Laboratory
Mckee Medical Center Laboratory
North Colorado Medical Center Laboratory
