Useful For
Suggests clinical disorders or settings where the test may be helpful
Precise measurement of glomerular filtration rate and renal plasma flow
| Test Id |
Reporting Name |
Available Separately |
Always Performed |
| IOTC |
Iothalamate Clearance |
No
|
Yes |
| PAHCC |
PAH Clearance |
No
|
Yes |
Method Name
A short description of the method used to perform the test
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Yes
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Standard Renal Clearance
Specimen Type
Describes the specimen type validated for testing
Plasma Na Heparin
Urine
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
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.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| All specimens will be evaluated at Mayo Clinic Laboratories for test suitability. |
| Specimen Type |
Temperature |
Time |
Special Container |
|
Plasma Na Heparin |
Refrigerated (preferred) |
7 days |
|
|
|
Frozen |
7 days |
|
|
Urine |
Refrigerated (preferred) |
7 days |
|
|
|
Frozen |
7 days |
|
Useful For
Suggests clinical disorders or settings where the test may be helpful
Precise measurement of glomerular filtration rate and renal plasma flow
The assessment of glomerular filtration rate (GFR) is an important parameter of renal function utilized by clinicians in the care of patients with varying renal diseases, and for clinical research when precise assessment of renal function is necessary. The GFR is the sum of all the filtration rates of the individual nephrons within the kidney and, as such, reflects the number of functioning nephrons.
GFR can fall due to a chronic renal disease that causes a permanent loss of nephrons, or due to an acute renal injury that is potentially reversible. In addition, a decline in renal blood flow, ie, secondary to volume depletion, can result in a fall in GFR that is functional and (potentially) quickly reversible. GFR increases when factors that decreased renal blood flow are corrected, or the kidney heals after an acute injury. GFR also increases transiently during pregnancy, as well as in response to other physiologic stimuli that include hyperglycemia or a dietary protein load.
Measurement of GFR can be performed by several methodologies including creatinine clearance, iothalamate clearance, and inulin clearance. Of these methods, the latter 2 are significantly more accurate and reproducible than the former.
Renal clearance of inulin, a fructose polymer, has traditionally been considered the gold standard for determination of GFR. Disadvantages to the use of inulin are its high cost, limited availability, and analytical expense. Previous studies have shown close correlation between iothalamate and inulin GFR determinations. The short renal clearance test, which utilizes a subcutaneous injection of nonradiolabeled iothalamate and a single (1 hour) urine specimen, is the preferred method for measurement of GFR in most situations since it is less time consuming and less costly.
The Standard Renal Clearance test, which utilizes continuous intravenous infusion of iothalamate (or inulin) and additional urine and plasma collections, is an alternative means of measuring GFR and may be preferable in patients with low urine flows (eg, patients with severe liver failure).
The Standard Renal Clearance test also measures renal plasma flow (RPF). Intravenously administered para-aminohippurate (PAH) is used to determine RPF because PAH is nearly completely removed from the renal circulation in a single pass, by a combination of glomerular filtration and tubular secretion.
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
GLOMERULAR FILTRATION RATE
20 years: 87-141 mL/min/SA
(Iothalmate) Decreases by 4.95 mL/min/decade
< or = 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
Provides information to assist in interpretation of the test results
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%.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
A theoretical complication (one that has not been observed clinically to date) is transient suppression of thyroid function in premature and newborn infants. Therefore, a sensitive thyrotropin test is suggested approximately 23 weeks after a standard renal clearance test in that age group.
Because complete clearance of para aminohippurate (PAH) is dependent on tubular secretion, diseases or conditions that disproportionately affect renal tubular cells may decrease PAH clearance without necessarily causing a proportional decrease renal plasma flow. Therefore, PAH clearance may underestimate renal perfusion flow in patients with selected diseases that affect renal tubulointerstitium.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Seegmiller JC, Burns BE, Fauq AH, et al: Iothalamate quantification by tandem mass spectrometry to measure glomerular filtration rate. Clin Chem 2010;56:568-574
2. Slack TK, Wilson DM: Normal renal function CIN and CPAH in healthy donors before and after nephrectomy. Mayo Clin Proc 1976;51:296-300
3. Liedtke RR, Durate CG: Laboratory protocols and methods for the measurement of glomerular filtration rate and renal plasma flow. In Renal Function Tests. Edited by CG Duarte. Boston, Little Brown and Co., 1980, pp 49-63
4. Kasiske BL, Keane WF: Laboratory assessment of renal disease: clearence, urinalysis, and renal biopsy. In Brenner and Rector's The Kidney. Sixth edition. Edited by BM Brenner. Philadelphia, PA, WB Saunders Co, 2000, pp 1129-1142
5. Wilson DM, Bergert JH, Larson TS, Liedtke RR: GFR determined by nonradiolabeled iothalamate using capillary electrophoresis. Am J Kid Dis 1997;30:646-652
Method Description
Describes how the test is performed and provides a method-specific reference
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.
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
No
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Same day/1 to 4 days
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
7 days
Rochester
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
| Test Id |
Test Order Name |
Order LOINC Value
|
| STRC |
Standard Renal Clearance |
96403-1 |
| Result Id |
Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
| IOTC |
Iothalamate Clearance |
90995-2 |
| PAHC |
PAH Clearance |
96404-9 |
| FILT |
Filtration Fraction |
96405-6 |
| CMT13 |
Comment |
77202-0 |