Cortisol, urinary free, 24-hour urine-13493
Test info
The diagnosis of Cushing syndrome (CS) requires evidence of cortisol hypersecretion.
Not useful in the evaluation of adrenal insufficiency (AI).
Specimen
- Measure and record the total volume of the 24-hr collection
- Mix well
- Transfer a 100 mL aliquot to a Screw cap plastic container (sterile)
24 hr urine collection container with HCl
- Total volume
Ambient (preferred) - 14 days
Refrigerated - 14 days
Frozen - 14 days
Freeze/thaw cycles - stable x 3
Performance
Liquid chromatography tandem mass spectrometry (LC/MS-MS)
Clinical and Interpretive info
|
Age |
Male (µg/24h) |
Female (µg/24h) |
|
0 d - 1 yr |
not established |
not established |
|
2 – 5 yrs |
2 – 16 |
2 – 16 |
|
6 – 11 yrs |
4 – 28 |
4 – 24 |
|
12 yrs |
4 – 36 |
4 – 36 |
|
13 - 17 yrs |
6 – 45 |
6 – 42 |
|
18 - 80 yrs |
5 – 64 |
6 – 42 |
|
> 80 yrs |
3 – 49 |
3 – 49 |
While serum cortisol levels fluctuate unpredictably and are strongly dependent on concurrent cortisol-binding globulin (CBG) levels, a 24-hour urine specimen integrates the cortisol production for an entire day and is not affected by CBG. Urinary cortisol reflects the portion of serum-free cortisol filtered by the kidney, and correlates well with cortisol secretion rate. The most common causes of CS are pituitary adenoma (65% to 70%), adrenal tumor (15% to 20%), and ectopic CS (10% to 15%).
Billing
Cortisol,F,ug/24hr: 7-7