What are the limitations of the free androgen index fai?

While the free androgen index fai is highly validated, it should not replace clinical judgment. OpiCalc provides the latest evidence-based limitations for the free androgen index fai to ensure safe bedside use and optimal diagnostic accuracy.

How does the free androgen index fai compare to other Endocrinology scores?

The free androgen index fai is a gold-standard diagnostic tool. OpiCalc provides side-by-side clinical guidance to help clinicians choose the most specific evidence-based tool for their patient's presentation.

Is the free androgen index fai free to use?

Yes. OpiCalc provides the free androgen index fai completely ad-free and optimized for mobile bedside use, ensuring you can calculate medical risk swiftly and without distraction.

Free androgen index fai Score and Guidance

CLINICAL REFERENCE

CLINICAL INSIGHT

When to Use

Screening for biochemical hyperandrogenism in women (Rotterdam criteria for PCOS).
Investigating hirsutism, acne, or androgenic alopecia.
Evaluating patients with menstrual irregularities.
Monitoring anti-androgen therapy efficacy.

CLINICAL INSIGHT

How it Works

Calculation

Unit Conversion

Important: Both Testosterone and SHBG must be in nmol/L. To convert Testosterone from ng/dL to nmol/L, multiply by 0.0347.

CLINICAL INSIGHT

Practical Pearls

Interpretation in Women

Range (%)	Interpretation
< 5.0	Normal (Typical for pre-menopausal women)
5.0 – 10.0	Mildly Elevated (Suggestive of PCOS)
> 10.0	Significant Hyperandrogenism

Wait, why SHBG?

Circulating testosterone is bound to SHBG (~66%) and Albumin (~33%). Only the remaining 1-2% is "free" and biologically active. Conditions like obesity, insulin resistance, or hypothyroidism decrease SHBG, thus increasing the portion of free testosterone even if Total Testosterone is normal. FAI captures this relationship.

CLINICAL INSIGHT

Evidence Base

Primary Source

A critical evaluation of simple methods for the estimation of free testosterone in serum.

Vermeulen A, et al.J Clin Endocrinol Metab1999

When to Use

When to Use

How it Works

Calculation

Unit Conversion

Practical Pearls

Interpretation in Women

Wait, why SHBG?

Evidence Base

Primary Source

Free Androgen Index (FAI)

When to Use

When to Use

How it Works

Calculation

Unit Conversion

Practical Pearls

Interpretation in Women

Wait, why SHBG?

Evidence Base

Primary Source

Free Androgen Index (FAI)

Clinical Evidence and Methodology

When to Use

When to Use

How it Works

Calculation

Unit Conversion

Practical Pearls

Interpretation in Women

Wait, why SHBG?

Evidence Base

Primary Source

Free Androgen Index (FAI)

Clinical Evidence and Methodology

When to Use

When to Use

How it Works

Calculation

Unit Conversion

Practical Pearls

Interpretation in Women

Wait, why SHBG?

Evidence Base

Primary Source

Free Androgen Index (FAI)