How often to repeat eGFR on a long 850
Obtain eGFR at least annually in everyone on Glucophage. Check more often in people at risk of decline, including many older adults.
A stable 850 for five years does not retire the draw. The filtration number is the board tag that keeps the bottle legal.
Age 65 or older sits on the lactic-acidosis risk list. That is a reason to draw eGFR more often, not a reason to refuse 850 by birthday alone.
Why eGFR is drawn before any 850
Assess renal function prior to initiation. Metformin is excreted unchanged in urine. Starting Glucophage 850 mg without a filtration number skips the first labelled stop.
The order scan already said the visit comes first. This page names the actual cuts.
What below 30 mL/min/1.73 m2 means
Severe renal impairment at that threshold is a contraindication. Discontinue if eGFR later falls below 30. Accumulation is the lactic-acidosis setup the boxed warning is about.
A 'my sugar is fine so I skipped the bloodwork' year is how rare acidosis stories get a kidney prologue. The number still wins over a pretty A1C.
Why 30-45 is not a start band
Initiation is not recommended when eGFR sits between 30 and 45. That is stricter than 'start low.' It is a do-not-open-a-new-bottle line.
People already on metformin who slide into that band need a benefit-risk talk, not an automatic extra 850. Sliding under 30 ends the talk: stop.
Where contrast and acidosis go after the cuts
Iodinated dye holds depend on these numbers plus route and comorbidity. File that on the contrast scan. The boxed picture is lactic acidosis.
The 850 panel repeats 45 and 30 in short form. This scan is the kidney job only.
What to do if the number falls after a stable 850
Reassess the whole chart: diuretics, ACE inhibitors, dehydration, contrast. The 850 is one line. The kidney is shared. Loop and ACE panels on this site are other organs, not this scan's job.
Dose reductions or holds are clinic arithmetic. Do not invent a half-tablet schedule from a forum because last year's eGFR was 52 and this year's is 41.