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HelpTest Code STRC Standard Renal Clearance, Plasma and Random Urine
Specimen Required
Contact MLI for approval prior to ordering this test.
Both plasma and urine are required.
Specimen Type: Plasma
Container/Tube: 6-mL Green top (sodium heparin)
Specimen Volume: 3-4 mL
Collection Instructions: Label specimen as plasma.
Specimen Type: Urine
Container/Tube: Sarstedt 5 mL Aliquot Tube (T914)
Specimen Volume: 5 mL
Collection Instructions:
1. Collect a random urine collection.
2. No preservative.
3. Label specimen as urine.
Useful For
Precise measurement of glomerular filtration rate and renal plasma flow
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| IOTC | Iothalamate Clearance | No | Yes |
| PAHCC | PAH Clearance | No | Yes |
Method Name
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Specimen Type
Plasma Na HeparinUrine
Specimen Minimum Volume
2 mL plasma/5 mL urine
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Na Heparin | Refrigerated (preferred) | 7 days | |
| Frozen | 7 days | ||
| Urine | Refrigerated (preferred) | 7 days | |
| Frozen | 7 days |
Reject Due To
| All specimens will be evaluated at Mayo Clinic Laboratories for test suitability. |
Reference Values
GLOMERULAR FILTRATION RATE
20 years: 87-141 mL/min/SA
(Iothalmate) Decreases by 4.95 mL/min/decade
≤ 19 years: Not established
20 years: 87-141
21 years: 86-140
22 years: 86-140
23 years: 85-139
24 years: 85-139
25 years: 84-138
26 years: 84-138
27 years: 83-137
28 years: 83-137
29 years: 82-136
30 years: 81-136
31 years: 81-136
32 years: 81-135
33 years: 80-135
34 years: 80-134
35 years: 79-134
36 years: 79-133
37 years: 78-133
38 years: 78-132
39 years: 77-132
40 years: 77-131
41 years: 76-131
42 years: 76-130
43 years: 75-130
44 years: 75-129
45 years: 74-129
46 years: 74-128
47 years: 73-128
48 years: 73-127
49 years: 72-127
50 years: 72-126
51 years: 72-126
52 years: 71-125
53 years: 71-125
54 years: 70-124
55 years: 70-124
56 years: 69-123
57 years: 69-123
58 years: 68-122
59 years: 68-122
60 years: 67-121
61 years: 67-121
62 years: 66-120
63 years: 66-120
64 years: 65-119
65 years: 65-119
66 years: 65-119
67 years: 64-118
68 years: 64-118
69 years: 63-117
70-150 years: 62-116
PARA-AMINOHIPPURATE (PAH) CLEARANCE
PAH Clearance
0-19 years: not established
20-29 years: >448 mL/min/SA
30-39 years: >413 mL/min/SA
40-49 years: >378 mL/min/SA
50-59 years: >343 mL/min/SA
60-69 years: >308 mL/min/SA
70-79 years: >273 mL/min/SA
80-89 years: >238 mL/min/SA
90-99 years: >203 mL/min/SA
Note: Reference range decreases by 35mL/decade.
FILTRATION FRACTION
>or=16 years: 18-22%
Interpretation
Iothalamate Clearance:
Low glomerular filtration rate (GFR) values indicate abnormal renal function, which may be either reversible/transient or irreversible/permanent. GFR tends to decline with age.
Para-Aminohippurate (PAH) Clearance:
The renal clearance of PAH, calculated from measurements of PAH in serum and timed urine specimens, equals renal plasma flow (RPF). However, it is important to note that only 85% to 90% of PAH is cleared from the circulation in a single pass, so the PAH clearance may underestimate RPF by 10% to 15%.
Filtration Fraction (FF):
The FF is the fraction of plasma perfusing the kidneys that is filtered (FF=GFR/RPF). Under normal conditions, FF is approximately 20%. Values significantly different from this provide an index to changes in GFR relative to RPF. For example, in states of decreased renal perfusion due to congestive heart failure, both RPF and GFR are decreased, whereas the FF is >20%.
Method Description
Blood and timed urine samples are obtained after continuous intravenous infusion of iothalamate and para-aminohippurate (PAH), the patient is allowed to equilibrate. Both iothalamate and PAH are measured by liquid chromatography-tandem mass spectrometry (LC/MS/MS). Renal clearance is calculated using the standard clearance formula.
Day(s) Performed
Monday through Friday
Report Available
Same day/1 to 4 daysSpecimen Retention Time
7 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
82542 x 7
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| STRC | Standard Renal Clearance | 96403-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| IOTC | Iothalamate Clearance | 90995-2 |
| PAHC | PAH Clearance | 96404-9 |
| FILT | Filtration Fraction | 96405-6 |
| CMT13 | Comment | 77202-0 |