Patient guide · Nuclear medicine
Renogram scan, nuclear medicine test of kidney function and drainage.
A renogram is a nuclear medicine scan using an IV radiotracer (MAG3 or DTPA) to measure kidney perfusion, function and drainage — for obstruction (PUJ), split renal function and renovascular hypertension workup.
Reviewed by Pulse Atlas Editorial Board, · Published 2026-07-30 · Next review 2027-07-30 · 5 min read
Key facts
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Definition
Nuclear medicine kidney function and drainage scan.
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IV radiotracer
MAG3 (preferred) or DTPA administered intravenously.
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Study duration
30–45 minute dynamic acquisition.
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Furosemide challenge
Diuretic used to differentiate true obstruction.
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Split function
Percentage contribution reported per kidney.
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Complementary imaging
Complements CT urography and MRI.
Diagnosis pathway
From referral to report — what to expect.
A renogram is a short, well-tolerated day-case study. These are the seven practical steps.
- 01
Nephrology or urology consultation
Clinical assessment establishes the question the renogram is meant to answer.
- 02
Hydration
Good hydration before the study helps tracer clearance and drainage assessment.
- 03
IV cannulation
A small cannula is placed, usually in the arm, for tracer and diuretic delivery.
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Radiotracer administration
MAG3 (or DTPA) is injected as imaging begins.
- 05
Dynamic imaging
The gamma camera acquires images for around 30 minutes as tracer passes through the kidneys.
- 06
Furosemide challenge
IV furosemide is given to distinguish obstruction from a dilated but draining system.
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Structured report
Split function, transit times and drainage curves are reported to the referring team.
What it shows
When a renogram is the right test.
A renogram answers questions that anatomical imaging cannot — how each kidney is functioning, and whether a dilated system is truly obstructed.
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Split renal function
Percentage contribution of each kidney to overall function.
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PUJ obstruction
Pelviureteric junction obstruction with T1/2 greater than 20 minutes on diuretic renogram.
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VUJ obstruction
Vesicoureteric junction obstruction affecting drainage into the bladder.
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Renovascular hypertension
Captopril renogram supports workup for renal artery stenosis.
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Renal transplant function
Assessment of perfusion and drainage in a transplanted kidney.
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Renal scarring
Focal loss of function suggestive of scarring from reflux or infection.
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Duplex kidney function
Separate assessment of the upper and lower moiety of a duplex system.
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Red flag: obstructed transplant kidney — urgent transplant team
An obstructed transplant kidney is a same-day transplant-team problem.
Red flags
When kidney findings need urgent attention.
These presentations bypass the standard outpatient pathway — same-day specialist review is warranted.
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Obstructed transplant kidney
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Acute pyelonephritis with obstruction
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Solitary kidney with obstruction
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Bilateral PUJ obstruction
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Post-transplant rejection
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Renal artery stenosis with flash pulmonary oedema
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Acute kidney injury with obstruction
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Sepsis with obstructed kidney
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Renal trauma
Treatment options
What follows a renogram finding.
Management depends on the specific finding, the affected kidney and the wider clinical picture — decided by urology and nephrology, not the scan alone.
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Watchful waiting
Partial or non-progressive obstruction may be monitored with serial imaging.
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Pyeloplasty for PUJ obstruction
Surgical reconstruction of the pelviureteric junction to restore drainage.
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Ureteric stent
JJ stent placed cystoscopically to bypass an obstructing lesion.
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Percutaneous nephrostomy
Radiologically placed drain when antegrade decompression is required.
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Antihypertensive optimisation
Medical management of renovascular hypertension.
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Renal artery stenting
Endovascular intervention in selected cases of renal artery stenosis.
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Structured urology / nephrology follow-up
Serial function and imaging under the referring specialist.
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Multi-disciplinary team review
Complex cases discussed jointly by urology, nephrology and radiology.
Frequently asked
What patients ask about a renogram.
Common questions on the study itself, radiation, medication and the captopril variant.
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What does a renogram scan show?
It measures how well each kidney takes up, filters and drains a small dose of intravenous radiotracer — giving split function and a drainage curve for each side.
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Is a renogram painful?
No. It requires an IV cannula for the tracer and diuretic, but the imaging itself is painless — you lie still under a gamma camera.
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How long does the scan take?
Typical acquisition is 30–45 minutes, with a furosemide challenge added when obstruction is the clinical question.
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Is the radiation dose significant?
The effective dose from a MAG3 renogram is small — comparable to background radiation over a few months — and is justified by the clinical question.
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Do I need to stop any medication?
ACE inhibitors and angiotensin receptor blockers are usually stopped before a captopril renogram; diuretics may need adjustment. Your referring clinician will advise.
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What is a captopril renogram?
A renogram performed after an oral ACE inhibitor to unmask haemodynamically significant renal artery stenosis as part of a renovascular hypertension workup.
Sources
Clinical guidelines behind this guide.
- British Nuclear Medicine Society. Clinical guidelines on renal imaging.
- European Association of Nuclear Medicine. Procedure guidelines for renography.
- Society of Nuclear Medicine and Molecular Imaging. Practice guidelines for renal scintigraphy.
- NICE. Renovascular disease — clinical knowledge summary.
Related tests
Looking for a different test?
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MAG3 renogram
The tubular-secretion tracer variant most often used in adults.
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Kidney ultrasound
First-line anatomical imaging of the kidneys and collecting systems.
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CT urography
Cross-sectional imaging of the urinary tract, including calculi.
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In practice, in London
Booking renogram scan privately in London — what actually happens
With renogram scan, the London question is usually about report turnaround and the radiologist reading it — not whether the scan is available. The NHS route for renogram scan is thorough, but the queue is real. Most patients we speak with have been told to expect anywhere from a handful of weeks to several months, depending on their local trust and how the referral is graded. Going private in London usually collapses that window to a matter of days — often the same week if the diary allows. It isn’t about jumping a queue so much as buying time back while you still have the flexibility to plan around it.
Once you’re in the private system for renogram scan, the pace picks up noticeably. Consultant slots run to time, imaging is usually available in the same building or a short walk away, and the report comes back typed and detailed. It’s the coordination that tends to feel different — one person on the other end of the phone, not a switchboard. For renogram scan specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.
Where a good concierge earns its keep is in the matching. There are dozens of consultants in London who see renogram scan — but not all of them are the right fit for every case. We narrow it down based on subspecialty, insurer coverage, the specific question being asked, and whether continuity into treatment matters. The right first appointment saves you from repeating yourself later.