Elecsys Cortisol III

K242505 · Roche Diagnostics · JFT · Jul 17, 2025 · Clinical Chemistry

Device Facts

• Record ID: K242505
• Device Name: Elecsys Cortisol III
• Applicant: Roche Diagnostics
• Product Code: JFT · Clinical Chemistry
• Decision Date: Jul 17, 2025
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 862.1205
• Device Class: Class 2

Indications for Use

Immunoassay for the in vitro quantitative determination of cortisol in human urine. 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 cobas e immunoassay analyzers.

Device Story

Elecsys Cortisol III is an in vitro diagnostic immunoassay for quantitative cortisol measurement in human urine; used on cobas e 801 analyzers in clinical laboratory settings. Principle of operation: competition test; sample incubated with biotinylated monoclonal anti-cortisol antibody; subsequent addition of streptavidin-coated microparticles and ruthenium-labeled cortisol derivative. Microparticles magnetically captured on electrode; voltage application induces chemiluminescent emission measured by photomultiplier. Results determined via instrument-specific calibration curve. Output provides quantitative cortisol concentration to assist clinicians in diagnosing and managing adrenal gland functional disorders.

Clinical Evidence

Bench testing only. Performance evaluated via precision (CLSI EP05-A3), linearity (CLSI EP06-Ed2), and interference/cross-reactivity (CLSI EP07). Method comparison against predicate (N=125) showed Passing Bablok slope 1.051, intercept -0.810, r=0.933. Reference range established using 144 healthy subjects (2.5th-97.5th percentile: 24.8–238 nmol/24h). No clinical prospective/retrospective studies performed.

Technological Characteristics

ECLIA-based immunoassay. Reagents: streptavidin-coated microparticles, biotinylated monoclonal anti-cortisol antibody, ruthenium-labeled cortisol derivative. Buffer: MES (pH 6.0). Detection: chemiluminescence via photomultiplier. Instrument: cobas e 801 analyzer. Traceable to NIST SRM 921a. Software: instrument-specific calibration and master curve via cobas link.

Indications for Use

Indicated for the in vitro quantitative determination of cortisol in human urine to assist in the recognition and treatment of functional disorders of the adrenal gland. No specific patient population age or gender restrictions are provided.

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

• Architect Cortisol Assay (K062204)

Submission Summary (Full Text)

{0}

FDA U.S. FOOD & DRUG ADMINISTRATION

# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY

ASSAY ONLY

## I Background Information:

A 510(k) Number

K242505

B Applicant

Roche Diagnostics

C Proprietary and Established Names

Elecsys Cortisol III

D Regulatory Information

| Product Code(s) | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| JFT | Class II | 21 CFR 862.1205 - Cortisol (Hydrocortisone And Hydroxycorticosterone) Test System | CH - Clinical Chemistry |

## II Submission/Device Overview:

A Purpose for Submission:

New Device

B Measurand:

Cortisol

C Type of Test:

Quantitative, Enzyme Immunoassay

Food and Drug Administration

10903 New Hampshire Avenue

Silver Spring, MD 20993-0002

www.fda.gov

{1}

K242505 - Page 2 of 12

# III Intended Use/Indications for Use:

## A Intended Use(s):

See Indications for Use below.

## B Indication(s) for Use:

Immunoassay for the in vitro quantitative determination of cortisol in human urine. 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 cobas e immunoassay analyzers.

## C Special Conditions for Use Statement(s):

Rx - For Prescription Use Only

## D Special Instrument Requirements:

Cobas e 801 analyzer

# IV Device/System Characteristics:

## A Device Description:

The Elecsys Cortisol III immunoassay reagent working solutions consist of the following:

- **M** Streptavidin-coated microparticles (transparent cap), 1 bottle, 12.4 mL: Streptavidin-coated microparticles 0.72 mg/mL; preservative.
- **R1** Anti-cortisol-Ab-biotin (gray cap), 1 bottle, 21.0 mL: Biotinylated monoclonal anti-cortisol antibody (mouse) 18 ng/mL; danazol 20 pg/mL; MES buffer 100 mmol/L, pH 6.0; preservative.
- **R2** Cortisol-peptide-Ru(bpy) (black cap), 1 bottle, 21.0 mL: Cortisol derivative (synthetic), labeled with ruthenium complex, 5 ng/mL; danazol 20 pg/mL; MES buffer 100 mmol/L, pH 6.0; preservative.

MES = 2-morpholino-ethane sulfonic acid

## B Principle of Operation:

The Elecsys Cortisol III immunoassay makes use of a competition test principle with the following steps for a total duration of 18 minutes:

1st incubation: By incubating the sample (6 µL) with a cortisol-specific biotinylated monoclonal antibody, immunocomplexes are formed, the amount of which is dependent upon the analyte concentration in the provided sample.

{2}

2nd incubation: After addition of streptavidin-coated microparticles and a cortisol-derivative labeled with a ruthenium complex a), the still-vacant sites of the biotinylated antibodies become occupied, with formation of an antibody-hapten complex. The entire complex becomes bound to the solid phase via interaction of biotin and streptavidin.

The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell II M. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier.

Results are determined via a calibration curve which is instrument-specifically generated by two-point calibration and a master curve provided via the cobas link.

## V Substantial Equivalence Information:

A Predicate Device Name(s):

Architect Cortisol Assay

B Predicate 510(k) Number(s):

K062204

C Comparison with Predicate(s):

| Device & Predicate Device(s): | K242505 | K062204 |
| --- | --- | --- |
| Device Trade Name | Elecsys Cortisol III | Architect Cortisol Assay |
| General Device Characteristic Similarities | | |
| Intended Use/Indications For Use | Immunoassay for the in vitro quantitative determination of cortisol | Same |
| Measurand | Cortisol | Same |
| General Device Characteristic Differences | | |
| Sample Type | Urine | Serum, plasma or urine |
| Reportable Range | 0.73 – 18.1 μg/dL (20.0 – 500 nmol/L) | 0.8 – 59.8 μg/dL |
| Detection Method | electrochemiluminescence immunoassay “ECLIA” | chemiluminescent microparticle immunoassay (CMIA) |

## VI Standards/Guidance Documents Referenced:

- CLSI EP05-A3: Evaluation of Precision of Quantitative Measurement Procedures; Approved Guideline - Third Edition
- CLSI EP09c-Ed3: Measurement Procedure Comparison, and Bias Estimation using Patient Samples; Approved Guideline

K242505 - Page 3 of 12

{3}

- CLSI EP17-A2: Evaluation of Detection Capability for Clinical laboratory Measurement procedures; Approved Guideline
- CLSI EP06-Ed2: Evaluation of the Linearity of Quantitative Measurement Procedures
- CLSI EP07-Ed3: Interference Testing in Clinical Chemistry.
- CLSI EP28-A3c: Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline - Third Edition

## VII Performance Characteristics (if/when applicable):

## A Analytical Performance:

1. Precision/Reproducibility:

### Precision

Precision studies were conducted for the Elecsys Cortisol III assay to evaluate repeatability (within-run precision) and intermediate precision (within-laboratory precision) according to CLSI EP05-A3. A precision study was conducted with one reagent lot for the Elecsys Cortisol III assay on one cobas e 801 analyzer to evaluate repeatability (within-run precision) and intermediate precision (within-laboratory precision) according to CLSI EP05-A3. Four human urine samples (24-hour urine) and two levels of PreciControl Cortisol Urine controls were tested in two replicates per run, two runs per day for 21 days. The results are summarized below.

| Sample | Mean (μg/dL) | Repeatability (within-run) | | Intermediate Precision (within-lab) | |
| --- | --- | --- | --- | --- | --- |
| | | SD (μg/dL) | CV (%) | SD (μg/dL) | CV (%) |
| Human Urine 1 | 3.22 | 0.087 | 2.7 | 0.12 | 3.8 |
| Human Urine 2 | 8.56 | 0.20 | 2.3 | 0.25 | 2.9 |
| Human Urine 3 | 10.7 | 0.21 | 2.0 | 0.34 | 3.2 |
| Human Urine 4 | 16.4 | 0.34 | 2.1 | 0.53 | 3.2 |
| Control 1 | 7.39 | 0.15 | 2.0 | 0.18 | 2.5 |
| Control 2 | 13.6 | 0.33 | 2.4 | 0.41 | 3.0 |

### Reproducibility

A multi-site, multi-lot reproducibility experiment was performed according to CLSI EP05-A3 using four human urine (24 hr urine) samples and two urine control levels. Data were collected at two external sites each using one reagent lot and one external site using three reagent lots. Twenty five (25) repeated measurements were performed for each sample appearing combination of sample (concentration level, site and lot) with five repetitions per day for five days on a cobas e 801 analyzer. Testing was completed at all three sites for a total $N = 125$. Results are summarized in the table below.

K242505 - Page 4 of 12

{4}

| Sample | N | Mean (μg/dL) | Reproducibility | |
| --- | --- | --- | --- | --- |
| | | | SD (μg/dL) | CV (%) |
| Human Urine 1 | 125 | 7.58 | 0.16 | 2.1 |
| Human Urine 2 | 125 | 11.67 | 0.26 | 2.2 |
| Human Urine 3 | 125 | 15.04 | 0.32 | 2.1 |
| Human Urine 4 | 125 | 17.58 | 0.44 | 2.5 |
| Control 1 | 125 | 7.54 | 0.17 | 2.3 |
| Control 2 | 125 | 13.63 | 0.33 | 2.4 |

# 2. Linearity:

Linearity was evaluated using three spiked high analyte human urine samples diluted with low analyte human urine sample on the cobas e 801 analyzer according to CLSI EP06-Ed2. The dilution series contained a minimum of 9 concentrations ranging from approximately 0.22 to $193.58~\mu \mathrm{g / dL}$ (6.1 to $534~\mathrm{nmol / L}$ ) to cover the measuring range. Samples were assayed in a 4-fold determination within a single run. Linear regression results representative of the assay linearity is as follows:

| | Linear Regression |
| --- | --- |
| Range | 6.26 – 534 nmol/L |
| Intercept | 0 |
| Slope | 0.960 |
| Correlation Coefficient (Pearson's r) | 0.999 |
| R2 | 0.995 |

The results support the claimed measuring interval of 0.73-18.1 $\mu$ g/dL (20-500 nmol/L).

# 3. Analytical Specificity/Interference:

# Interference

Interfering substances (endogenous and exogenous) were tested according to CLSI EP07 using 3 human urine samples (24 hour urine) containing low, mid, and high concentrations ( $\sim 20$ , $\sim 200$ , and $\sim 450$ nmol/L) of cortisol, with the exception of hydrochlorothiazide (HCTZ), Lisinopril, and Metformin which were tested using two human urine samples (24-hour urine) containing approximately $25$ nmol/L and $375$ nmol/L. Each potential interfering substance was spiked into the urine samples with one aliquot left unspiked to serve as the control. Samples were tested in replicates of five. The results are summarized below.

K242505 - Page 5 of 12

{5}

Exogenous Substances

| Interferent | Highest Concentration of substance tested which demonstrated no significant interference |
| --- | --- |
| Bilirubin | ≤ 1130 μmol/L or ≤ 66 mg/dL |
| Hemoglobin | ≤ 0.621 mmol/L or ≤ 1000 mg/dL |
| Intralipid | ≤ 2000 mg/dL |
| Biotin | ≤ 204658 nmol/L or ≤ 50000 ng/mL |
| Rheumatoid factors | ≤ 1200 IU/mL |
| IgG | ≤ 7.0 g/dL |

Exogenous Substances

| Interferent | Highest Concentration of substance tested which demonstrated no significant interference (mg/dL) |
| --- | --- |
| Amlodipine | 0.008 |
| Betamethasone | 0.0345 |
| Beclomethasone | 0.000631 |
| Budenoside | 0.00063 |
| Canrenone | 0.075 |
| Dexamethasone | 1.20 |
| Fludrocortisone | 0.120 |
| Fluticasone propionate | 0.0003 |
| HCT (hydrochlorothiazide) | 4.77 |
| Lisinopril | 27 |
| Losartan potassium | 0.092 |

K242505 - Page 6 of 12

{6}

The sponsor has included the following limitations in the labeling:

In rare cases, interference due to extremely high titers of antibodies to analyte-specific antibodies, streptavidin or ruthenium can occur. These effects are minimized by suitable test design.

## Biotin Interference

To evaluate the candidate device’s susceptibility to biotin interference, biotin was spiked into urine samples containing different concentrations of cortisol (26, 200, and 365 ng/mL). Samples were assay in multiple replicates. The results are summarized below.

| Sample (nmol/L) | Biotin concentration (ng/mL) | | | | |
| --- | --- | --- | --- | --- | --- |
| | 10,000 | 20,000 | 30,000 | 40,000 | 50,000 |
| 25.9 | +0.3 nmol/L | -0.1 nmol/L | +0.7 nmol/L | +0.9 nmol/L | +2 nmol/L |
| 206 | +1% | +2% | +5% | +5% | +6% |
| 365 | +1% | +2% | +5% | +4% | +5% |

K242505 - Page 7 of 12

{7}

| Sample (nmol/L) | Biotin concentration (ng/mL) | | | | |
| --- | --- | --- | --- | --- | --- |
| | 60,000 | 70,000 | 80,000 | 90,000 | 100,000 |
| 25.9 | +2 nmol/L | +3 nmol/L | +6 nmol/L | +10 nmol/L | +60 nmol/L |
| 206 | +11% | +12% | +17% | +23% | +88% |
| 365 | +6% | +11% | +17% | +35% | +99% |

The sponsor has included the following limitations in the labeling:

Specimens with biotin concentrations up to 50,000 ng/mL demonstrated ≤ 4.2 nmol/L bias (absolute deviation) for samples with initial value 10.0-42 nmol/L and ≤ 10% bias for samples with initial value > 42-500 nmol/L in cortisol results on the cobas e 801 analyzer. Biotin concentration greater than 50,000 ng/mL can lead to falsely elevated cortisol results on the cobas e 801 analyzer.

The highest urine concentrations of biotin reported in literature for subjects consuming supplements of 20 mg per day vary with one study reporting up to 31,700 ng/mL in 24 hours (Goodrum et al, 2023) and another study reporting up to 3120 ng/mL in 24 hours (Zempleni & Mock, 1999). Patients may take supplements as high as 300 mg per day, however, the urinary concentrations resulting from higher-dose biotin supplements have not been established in the literature.

At concentrations corresponding to the daily therapeutic dose, the special drugs prednisolone and hydrocortisone caused elevated concentrations of cortisol. For the special drug 6-methylprednisolone, no interference was observed for concentrations ≤ 0.157 mg/dL

## Cross-Reactivity Study

A cross-reactivity study was conducted according to CLSI EP07 to evaluate the potential cross-reacting compounds using human urine (24-hour urine) with a low analyte level (~0.6 μg/dL). One aliquot of urine sample was spiked with potential cross-reactants at the specified concentrations below and the other aliquot was left unspiked to serve as the control. Samples were measured in the presence and absence of the potential cross-reactants and cross-reactivity was calculated with one lot of reagent on the cobas e 801 analyzer. Cross reactivity was calculated according to the formula:

$$
\% \text{Cross-reactivity} = ((\text{Mean analyte concentration of spiked sample} - \text{mean analyte concentration of unspiked sample}) / (\text{Spiked concentration of cross-reactant}) \times 100\%
$$

The following cross-reactivities were found at the respective cross-reactant concentration tested with a cortisol concentration of approximately 17 nmol/L (0.6 μg/dL).

K242505 - Page 8 of 12

{8}

| Cross-Reactant | Concentration tested μg/dL | Cross reactivity % |
| --- | --- | --- |
| 11-Deoxy-Corticosterone | 100 | 0.174 |
| 11-Deoxy-Cortisol | 50 | 24.3 |
| 17a-Hydroxyprogesterone | 1000 | 0.412 |
| 21-Deoxy-Cortisol | 100 | 2.33 |
| Corticosterone | 750 | 0.368 |
| Cortisone | 500 | 1.49 |
| Androstendione | 100 | n.d. |
| DHEAS | 1000 | n.d. |
| DHEA | 1000 | n.d. |
| Progesterone | 1000 | 0.00930 |
| Testosterone | 1000 | n.d. |
| Estradiol | 1000 | n.d. |
| Estriol | 1000 | n.d. |
| Estrone | 1000 | n.d. |
| Aldosterone | 1000 | n.d. |
| Pregnenolone | 1000 | n.d. |
| 6 alpha-OH-Cortisol | 100 | 0.0417 |
| 6 beta-OH-Cortisol | 100 | 0.0173 |
| Cortisol-21 glucoronide | 1000 | n.d. |
| Allotetrahydrocortisol | 10 | n.d. |
| 17-alpha-Hydroxypregnenolone | 1000 | 0.0698 |
| 11-beta-Hydroxyprogesterone | 1000 | 0.0301 |
| Pregnanetriol | 1000 | 11.3 |
| Cortisol-21-sulfate | 1000 | n.d. |
| beta-Cortol | 1000 | n.d. |
| beta-Cortolone | 1000 | n.d. |
| Pregnanediol | 1000 | n.d. |
| Tetrahydrocortisol | 10 | n.d. |

Note: n.d. = not detectable

The sponsor has included the following limitations in the labeling:

Patients suffering from 21-hydroxylase deficiency exhibit elevated 21-deoxycortisol levels and this can also give rise to falsely elevated cortisol results.

K242505 - Page 9 of 12

{9}

During metyrapon tests, 11-deoxycortisol levels are elevated. Falsely elevated cortisol values may be determined due to cross-reactivity.

4. Assay Reportable Range:
0.73-18 ug/dL (20-500 nmol/L)

5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):

**Traceability**
The Elecsys Cortisol III assay has been standardized by an isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) based method. The method is traceable to the certified standard reference material SRM 921a Cortisol from the National Institute of Standards and Technology (NIST).

**On-Board Stability**
A stability study was conducted to ensure that the reagent performed consistently throughout the claimed in use/on board stability. All protocols and results were reviewed and found to be acceptable. The study results support the claims of 16 weeks.

6. Detection Limit:
The Limit of Blank (LoB), Limit of Detection (LoD), and Limit of Quantitation (LoQ) were determined according to CLSI guideline EP17-A2.

**Limit of Blank**
For determination of LoB, five analyte-free urine samples (24-hour urine) were measured using 3 reagent lots over ≥ three days in 6 runs with 2-fold determination per run for a total of 60 replicates per reagent lot on one cobas e 801 analyzer. LoB was calculated according to the parametric function as described in CLSI EP17-A2.

**Limit of Detection**
For determination of LoD, three reagent lots were evaluated on one cobas e 801 analyzer. Five low-level human urine samples (24-hour urine) were measured on one instrument over ≥ three days in 6 runs with a two-fold determination per run. LoD was calculated according to CLSI EP17-A2.

**Limit of Quantitation**
Determination of the LoQ of the Elecsys Cortisol III was performed using the cobas e 801 analyzer. A low-level sample set (ten 24-hour urine samples) of known measurand concentration was tested in two replicates (aliquots) on one instrument per run, for six runs over ≥ 3 days. LoQ was defined as the lowest amount of analyte in a sample that can be accurately quantitated with a total allowable error of ≤ 30%.

LoB, LoD and LoQ as reported in the labeling are shown below.

K242505 - Page 10 of 12

{10}

| Limits of Detection | Cortisol Concentration |
| --- | --- |
| LoB | 4.00 nmol/L (0.145 μg/dL) |
| LoD | 7.50 nmol/L (0.272 μg/dL) |
| LoQ | 10.0 nmol/L (0.363 μg/dL) |

7. Assay Cut-Off:

Not Applicable.

B Comparison Studies:

1. Method Comparison with Predicate Device:

A method comparison study of the Elecsys Cortisol III assay on the cobas e 801 analyzer (candidate device) with the predicate device was performed according to CLSI EP09-A3. Urine samples were measured with the Elecsys Cortisol III on the cobas e 801 analyzer and with the Architect Cortisol on Abbott Architect i2000 using one lot of each assay. 125 native urine samples (24-hour urine) that spanned the measuring range were tested with one run per sample. The Passing Bablok regression analysis results between the candidate device (dependent variable, y-axis) and the predicate device (x-axis, comparator) are shown below:

| N | Concentration Range (μg/dL)* | Slope | Intercept | Correlation coefficient (r) |
| --- | --- | --- | --- | --- |
| 125 | 0.837 – 17.7 | 1.051 | -0.810 | 0.933 |

*As measured by the candidate device

2. Matrix Comparison:

Not Applicable.

C Clinical Studies:

1. Clinical Sensitivity:

Not Applicable.

2. Clinical Specificity:

Not Applicable.

3. Other Clinical Supportive Data (When 1. and 2. Are Not Applicable):

Not Applicable.

K242505 - Page 11 of 12

{11}

D Clinical Cut-Off:

Not Applicable.

E Expected Values/Reference Range:

The US reference range study was performed using 144 apparently healthy subjects. The reference range was computed and reported as the 2.5th and 97.5th percentiles for pooled data from all study sites and with all sites combined. The 2.5th and 97.5th percentiles and corresponding intervals were computed using a nonparametric method as described in CLSI EP28-A3c.

| App. healthy males and females, no relevant medication | N | Median | 2.5th percentile (95% CI) | 97.5th Percentile (95% CI) |
| --- | --- | --- | --- | --- |
| 24-hour urine, μg per 24 hours | 144 | 26.4 | 8.98 | 86.28 |
| 24-hour urine, nmol per 24 hours | 144 | 72.8 | 24.8 | 238 |

The reference range for Elecsys Cortisol III in 24 hr urine will be listed 24.8 – 238 nmol/24 h in the “Expected values” section of the labeling. Sponsor stated the following in the labeling: “Each laboratory should investigate the transferability of the expected values to its own patient population and if necessary determine its own reference ranges.”

VIII Proposed Labeling:

The labeling supports the finding of substantial equivalence for this device.

IX Conclusion:

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

K242505 - Page 12 of 12