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Dr Pixel 2.0Women's imaging diagnosis

PLATFORM FOR EDUCATION AND DECISION SUPPORT IN WOMEN'S IMAGING

Choyke (validated)

Renal Pre-Contrast Screening (CT / MRI)

Answer the 6 questions below. All are required.

Answer all questions to generate the result.

Evidence

In a study of 1361 ambulatory patients, for detecting eGFR <45 mL/min/1.73 m² the questionnaire showed sensitivity of 92.9%, specificity of 65.3%, PPV of 2.7% and NPV of 99.9%. (Too et al., Eur J Radiol 2015)

The questionnaire also effectively stratifies nephrogenic systemic fibrosis (NSF) risk before gadolinium-enhanced MRI, with potential for cost savings and streamlined care. When the decision to administer gadolinium is based solely on questionnaire responses at the time of order, sensitivity of 71.4% for detecting eGFR <30 mL/min/1.73 m², specificity of 74.2%, PPV of 2.9% and NPV of 99.6% were observed. (Choyke et al., Radiology 2003)

Understand the screening

How renal pre-contrast screening (Choyke) works

The Choyke questionnaire identifies ambulatory patients at higher risk of renal dysfunction (eGFR <45 mL/min/1.73 m²), a level below which the risk of iodinated contrast-induced nephropathy increases significantly. It also stratifies nephrogenic systemic fibrosis (NSF) risk before gadolinium-enhanced MRI.

Why trust the questionnaire

Choyke diagnostic performance in ambulatory patients

Detecting eGFR < 45 mL/min/1.73 m² (iodinated contrast)
Sensitivity92.9%
Specificity65.3%
PPV2.7%
NPV99.9%
Too et al., Eur J Radiol 2015 — 1361 ambulatory patients
Detecting eGFR < 30 mL/min/1.73 m² (gadolinium)
Sensitivity71.4%
Specificity74.2%
PPV2.9%
NPV99.6%
Choyke et al., Radiology 2003

Choyke positive

Serum creatinine and eGFR calculation are recommended before IV contrast.

Choyke negative

Very low probability of relevant renal dysfunction. In the standard ambulatory setting, creatinine/eGFR is generally not required before IV contrast.

When NOT to use simplified screening

Do not use simplified screening in hospitalized/unstable patients, with suspected acute kidney injury, or when institutional protocol requires creatinine/eGFR. The questionnaire was validated in ambulatory patients and does not replace clinical judgment in higher-risk scenarios.

Common questions

Frequently asked questions about renal pre-contrast screening

What does the Choyke questionnaire assess?+
Six objective yes/no questions: previously diagnosed kidney problem, protein in urine (proteinuria), hypertension, diabetes, gout, and prior kidney surgery. A single "yes" answer already makes the result "Choyke positive".
What does "Choyke negative" mean?+
Very low probability of relevant renal dysfunction. In the standard ambulatory setting, creatinine/eGFR is generally not required before IV contrast — supported by a negative predictive value (NPV) of 99.9% in the Too et al. (2015) study for detecting eGFR <45 mL/min/1.73 m².
How reliable is the Choyke questionnaire?+
In a study of 1361 ambulatory patients (Too et al., Eur J Radiol 2015), for detecting eGFR <45 mL/min/1.73 m² it showed sensitivity of 92.9%, specificity of 65.3% and NPV of 99.9%. For gadolinium, assessing eGFR <30 mL/min/1.73 m² (Choyke et al., Radiology 2003), sensitivity was 71.4%, specificity 74.2% and NPV 99.6%.
When should I NOT use this simplified screening?+
In hospitalized/unstable patients, with suspected acute kidney injury, or when institutional protocol requires creatinine/eGFR. The questionnaire was validated only in ambulatory patients and does not replace clinical judgment in higher-risk scenarios.
Does the questionnaire apply to both iodinated contrast (CT) and gadolinium (MRI)?+
Yes. It was originally validated for screening before IV iodinated contrast (contrast-induced nephropathy risk) and also effectively stratifies nephrogenic systemic fibrosis (NSF) risk before gadolinium-enhanced MRI.
What should be done when the result is "Choyke positive"?+
Serum creatinine and eGFR calculation are recommended before IV contrast.