ELECSYS CORTISOL TEST SYSTEM

K070788 · Roche Diagnostics · NHG · Oct 5, 2007 · Clinical Chemistry

Device Facts

• Record ID: K070788
• Device Name: ELECSYS CORTISOL TEST SYSTEM
• Applicant: Roche Diagnostics
• Product Code: NHG · Clinical Chemistry
• Decision Date: Oct 5, 2007
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 862.1205
• Device Class: Class 2

Intended Use

Immunoassay for the in vitro quantitative determination of cortisol in human serum, plasma, urine, and saliva. The determination of cortisol is used for the recognition and treatment of functional disorders of the adrenal gland. The electrochemiluminescence immunoassay "ECLIA" is intended for use on Elecsys and cobas e immunoassay analyzers. Elecsys Cortisol CalSet is used for calibrating the quantitative Elecsys Cortisol assay on the Elecsys immunoassay analyzers.

Device Story

The Elecsys Cortisol Immunoassay is a quantitative, two-step sandwich immunoassay utilizing electrochemiluminescence (ECLIA) detection. It is designed for use on Elecsys and cobas e immunoassay analyzers. The system requires the use of a Salivette device for saliva sample collection. The assay operates by measuring cortisol levels in patient samples against a calibration curve generated by a 2-point calibration and a master curve provided via reagent bar code. The device is intended for clinical laboratory use to aid in diagnosing and managing adrenal gland functional disorders. Healthcare providers use the quantitative output to assess cortisol levels, which informs clinical decision-making regarding adrenal function. The system provides standardized, automated measurement of cortisol across multiple sample matrices.

Clinical Evidence

Bench testing only. Precision and sensitivity were evaluated using human saliva samples. The limit of quantitation (LoQ) was established at 8.5 nmol/L, defined as the concentration with a between-run coefficient of variation (CV) ≤ 20%. Precision studies demonstrated CVs ranging from 4.1% to 37.1% depending on concentration, with values below 8.5 nmol/L noted as unreliable. Reference ranges were established using saliva samples from 154 healthy individuals.

Technological Characteristics

Two-step sandwich immunoassay; electrochemiluminescence detection; streptavidin microparticles. Analyzers: Elecsys 1010/2010, MODULAR ANALYTICS E170, cobas e 411/601. Measuring range: 1.00–1750 nmol/L. Calibration: 2-point calibration with master curve via reagent bar code. Standards: CLSI EP17-A (LoD/LoQ), CLSI EP5-A2 (Precision).

Indications for Use

Indicated for in vitro quantitative determination of cortisol in human serum, plasma, urine, and saliva to assist in the recognition and treatment of functional disorders of the adrenal gland.

Regulatory Classification

Identification

A cortisol (hydrocortisone and hydroxycorticosterone) test system is a device intended to measure the cortisol hormones secreted by the adrenal gland in plasma and urine. Measurements of cortisol are used in the diagnosis and treatment of disorders of the adrenal gland.

Predicate Devices

• Elecsys Cortisol Assay (k043175)

Submission Summary (Full Text)

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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
ASSAY ONLY TEMPLATE

A. 510(k) Number:
k070788

B. Purpose for Submission:
Modification of assay performance claims for this assay in saliva samples

C. Measurand:
Cortisol

D. Type of Test:
Quantitative immunoassay

E. Applicant:
Roche Diagnostics

F. Proprietary and Established Names:
Elecsys Cortisol Immunoassay
Elecsys Cortisol CalSet

G. Regulatory Information:
1. Regulation section:
21 CFR 862.1205
21 CFR 862.1150
2. Classification:
II
3. Product code:
NHG
JIT

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4. Panel:
Chemistry (75)

H. Intended Use:

1. Intended use(s):
See Indications for use.

2. Indication(s) for use:
Elecsys Cortisol Immunoassay
Immunoassay for the in vitro quantitative determination of cortisol in human serum, plasma, urine, and saliva. The determination of cortisol is used for the recognition and treatment of functional disorders of the adrenal gland.

The electrochemiluminescence immunoassay “ECLIA” is intended for use on Elecsys and cobas e immunoassay analyzers.

Elecsys Cortisol CalSet
Elecsys Cortisol CalSet is used for calibrating the quantitative Elecsys Cortisol assay on the Elecsys immunoassay analyzers.

3. Special conditions for use statement(s):
These devices are for prescription use.

4. Special instrument requirements:
Elecsys 1010/2010, MODULAR ANALYTICS E170, or cobas e 411/601 analyzers

I. Device Description:
The Elecsys Cortisol Assay is a two step sandwich immunoassay with streptavidin microparticles and electrochemiluminescence detection. Results are determined using a calibration curve that is generated specifically on each instrument by a 2-point calibration and a master curve provided with the reagent bar code. The Elecsys Cortisol Assay is intended for use on the Elecsys Immunoassay Family of Analyzers. The Salivette device is required for the collection of saliva for testing. The Elecsys Cortisol CalSet is the calibration material for the assay.

J. Substantial Equivalence Information:

1. Predicate device name(s):

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Elecsys Cortisol Assay

2. Predicate K number(s):

k043175

3. Comparison with predicate:

| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Intended Use/Indications for Use | Quantitative determination of cortisol in human serum, plasma, urine, and saliva, for recognition and treatment of functional disorders of the adrenal gland | Same |
| | Calibration of the quantitative Elecsys Cortisol assay on the Elecsys immunoassay analyzers | Same |
| Test Principle | Competitive assay, electrochemiluminescent | Same |
| Measuring Range | 1 – 1750 nmol/L | Same |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Platforms | Elecsys 1010, Elecsys 2010, and MODULAR ANALYTICS E170, cobas e 411 and cobas e 601 analyzers | Elecsys 1010, Elecsys 2010, and MODULAR ANALYTICS E170 analyzers |
| Performance Claims | Limit of Blank ≤ 0.5 nmol/L Limit of Detection ≤ 1.0 nmol/L Limit of Quantitation 8.5 nmol/L | Analytical sensitivity < 0.5 nmol/L Functional sensitivity < 2.0 nmol/L |

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| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| | Between-run (saliva)
37.1% CV @ 0.93* nmol/L
7.2% CV @ 7.72 nmol/L
6.2% CV @ 16.9 nmol/L
4.9% CV @ 34.6 nmol/L
4.1% CV @ 42.5 nmol/L

*below LoD. Values below 8.5 nmol/L are not reliable as the coefficient of variation is >20%. | Between run (saliva)
33.4% CV @ 2.08 nmol/L
11.5% CV @ 8.05 nmol/L
7.1% CV @ 13.1 nmol/L
4.9% CV @ 34.6 nmol/L
4.1% CV @ 42.5 nmol/L |

## K. Standard/Guidance Document Referenced (if applicable):

CLSI EP17-A: “Protocol for Determination of Limits of Detection and Limits of Quantitation; Approved Guideline”

CLSI EP5-A2: Evaluation of Precision Performance of Quantitative Measurement Methods; Approved Guideline-Second Edition

## L. Test Principle:

The Elecsys Cortisol Assay is a two step sandwich immunoassay with streptavidin microparticles and electrochemiluminescence detection. Results are determined using a calibration curve that is generated specifically on each instrument by a 2-point calibration and a master curve provided with the reagent bar code. The Elecsys Cortisol Assay is intended for use on the Elecsys Immunoassay Family of Analyzers. The Salivette device is required for the collection of saliva for testing. The Elecsys Cortisol CalSet is the calibration material for the assay.

## M. Performance Characteristics (if/when applicable):

### 1. Analytical performance:

#### a. Precision/Reproducibility:

Between-run precision of the Elecsys Cortisol Test System was evaluated on Elecsys 2010 / cobas e 411 analyzer using a modified CLSI replication experiment. The protocol consisted of testing one replicate of each control (PC=PreciControl) or sample (HS=human saliva, SHS=spiked human saliva) per day for 10 days. Between-run precision was calculated according to EP5-A2.

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| Sample | N | Mean | SD (nmol/L) | CV (%) |
| --- | --- | --- | --- | --- |
| PCU 1 | 10 | 362.742 | 7.0723 | 1.9 |
| PCU 2 | 10 | 775.496 | 16.5517 | 2.1 |
| HS low | 10 | 2.082 | 0.6962 | 33.4 |
| HS medium | 10 | 8.049 | 0.9238 | 11.5 |
| HS high | 10 | 13.142 | 0.9375 | 7.1 |
| SHS low | 10 | 0.930* | 0.3449 | 37.1 |
| SHS medium | 10 | 34.574 | 1.6868 | 4.9 |
| SHS high | 10 | 42.47 | 1.76 | 4.1 |

*sample concentration is above the Limit of Blank, but below the Limit of Detection of this assay. (see Detection Limit section below). Values below 8.5 nmol/L are not reliable as the coefficient of variation is &gt;20%.

b. Linearity/assay reportable range:

The measuring range is 1.00-1750 nmol/L or 0.036-63.0 µg/dL (defined by the limit of detection and the maximum of the master curve). Performance of the device across the measuring range was established in k000270, k021218, and k043175. Performance information at the low end of the assay range is summarized in the Detection Limit section below.

c. Traceability, Stability, Expected values (controls, calibrators, or methods):

Established in k000270, k021218, and k043175.

d. Detection limit:

The limit of blank and limit of detection were determined in accordance with the CLSI EP17-A requirements.

The limit of blank (≤ 0.50 nmol/L or ≤ 0.018 µg/dL) is the 95th percentile value from n ≥ 60 measurements of an analyte-free sample over several independent series. The limit of blank corresponds to the concentration below which analyte-free samples are found with a probability of 95%.

The limit of detection (≤ 1.00 nmol/L or ≤ 0.036 µg/dL) is determined based on the limit of blank and the standard deviation of low concentration samples. The limit of detection corresponds to the lowest analyte concentration which can be detected (value above the limit of blank with a probability of 95%).

The limit of quantitation (8.50 nmol/L or 0.07 µg/dL) is the lowest analyte concentration that can be reproducibly measured with a between-run coefficient of variation of ≤ 20%. It has been determined using low concentration saliva samples.

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Because the %CV of low concentration samples is high, values below the LoQ should be reported with caution. The package insert has been revised to read: “When reporting values below 8.5 nmol/L, the client report should be annotated with the following information. “Values below 8.5 nmol/L are not reliable as the coefficient of variation is ≥20%.”

e. Analytical specificity:

Established under submissions k000270, k021218, and k043175.

f. Assay cut-off:

Not applicable.

2. Comparison studies:

a. Method comparison with predicate device:

Established under submissions k000270, k021218, and k043175.

b. Matrix comparison:

Established under submissions k000270, k021218, and k043175.

3. Clinical studies:

a. Clinical Sensitivity:

Not applicable

b. Clinical specificity:

Not applicable

c. Other clinical supportive data (when a. and b. are not applicable):

Not applicable

4. Clinical cut-off:

Not applicable

5. Expected values/Reference range:

The following values were determined in saliva samples from 154 healthy individuals (5th-95th percentile) using Elecsys Cortisol.

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Morning hours 8-10 AM: 1.90 - 19.1 nmol/L

Afternoon hours 2:30 - 3:30 PM: 2.05 - 11.9 nmol/L

## N. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.

## O. Conclusion:

The submitted information in this premarket notification is complete and supports a substantial equivalence decision.

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