NABP NAPLEX Exam - Topic 4 Question 112 Discussion

Actual exam question for NABP's NAPLEX exam

Question #: 112
Topic #: 4

LN is 84 YOM who is in hospital for a back surgery. His height is 5 feet and 4 inches, weight 85 kg and NKDA.

His past medical history includes hypertension, diabetes mellitus, major depression, hypothyroidism and chronic back pain. Post-op day 1, LN's medication includes Dexamethasone 8mg iv q6h with taper dosing, Ondansetron 4mg iv q6h prn for N/V, Levothyroxine 0.075mg po daily, Lisinopril 10mg po daily, Citalopram 20mg po daily, Docusate sodium / Senna 1 tab po twice a day, Bisacodyl 10mg suppository daily prn for constipation, Famotidine 20mg iv q12hr, Metoclopramide 10mg iv q6h, Metformin 500mg po bid, D51/2NS with 20K at 125mls/hour and Hydromorphone PCA at 0.2mg/hour of basal rate, demand dose 0.1mg. lock-out

every 6min, one hour limit 2.2mg/hour. Pertinent morning labs includes serum creatinine 1.4mg/dl, Mg 1.5mg/ dl, K 5.0mmol/L, Na 135mmol/L.

What is the reason for holding metformin in patients with reduced renal function?

AMetformin can cause acute renal failure

BMetformin can cause lactic acidosis

CMetformin can build up neurotoxin

DMetformin can cause hyperglycemia

EMetformin can cause hyperkalemia

Show Suggested Answer

Suggested Answer: B

Metformin is held in patients with reduced renal function due to an increased risk of lactic acidosis. Metformin has a Boxed Warning for lactic acidosis, which is a rare but serious metabolic complication. Lactic acidosis can occurs due to an accumulation of metformin (5 mcg/mL or more). It is fatal in about 50% of cases. Lactic acidosis has also been reported to occur in those with diabetes who have significant renal function impairment. Lactic acidosis occurs when there are elevated blood lactate levels of 5 mmol/L or more, decreased blood pH, electrolyte disturbances with an increased anion gap, and an increased lactate/pyruvate ratio. Normal lactic acid level <2.0 mmol/L.

by Deonna at Nov 20, 2025, 05:24 AM

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Avery

24 hours ago

I think D) is also relevant, but not the main reason here. Lactic acidosis is the priority.

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Dalene

6 days ago

I chose B as well. The risk increases with renal impairment.

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Chauncey

11 days ago

Definitely B. Metformin accumulation can lead to that, especially in older patients.

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Misty

16 days ago

I feel like A) could be a reason too, but lactic acidosis seems more critical.

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Art

22 days ago

Agreed, lactic acidosis is serious. We need to be careful with renal function.

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Jennifer

27 days ago

I think it's B) Metformin can cause lactic acidosis. That's a big concern with renal issues.

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Ula

2 months ago

Wait, does that mean he shouldn't be on it at all?

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Ronald

2 months ago

Metformin buildup can be serious, especially with creatinine at 1.4.

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Ashton

2 months ago

Really? I thought it was just for diabetes management.

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Vernell

2 months ago

B) Lactic acidosis, got it. Gotta watch out for that with metformin in renal impairment.

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Emelda

2 months ago

Haha, neurotoxin? Who comes up with these answer choices? B is the clear winner here.

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Talia

2 months ago

B) Definitely the right answer. Metformin and reduced kidney function is a dangerous combination.

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Golda

3 months ago

Lactic acidosis, really? That's a pretty serious complication. I'd better remember that one.

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Bulah

3 months ago

B) Metformin can cause lactic acidosis, which is a serious side effect in patients with reduced renal function.

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Rana

3 months ago

I feel like I’ve seen this before in lectures. Holding metformin is definitely related to lactic acidosis, but I’m not confident about the exact mechanisms involved.

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Broderick

3 months ago

I’m a bit confused about the options. I know metformin can cause issues with renal function, but I thought it was more about preventing complications rather than causing acute renal failure directly.

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Tresa

3 months ago

I practiced a similar question about metformin and renal function, and I believe the main concern is lactic acidosis, especially with elevated creatinine levels.

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Sabra

3 months ago

Okay, I think I've got it. Metformin is primarily eliminated through the kidneys, so in patients with reduced renal function, it can build up and increase the risk of lactic acidosis. That makes sense to me as the reason for holding it in this case.

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Theola

4 months ago

I think I remember that metformin is usually held in cases of renal impairment because of the risk of lactic acidosis, but I'm not completely sure.

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Galen

4 months ago

I'm a bit unsure on this one. There are a few potential reasons listed, and I'll need to think through each one carefully to determine the best answer. Hmm, I better re-read the question and information provided.

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Cordelia

4 months ago

Totally agree, B is the right choice!

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Hyun

4 months ago

Metformin can cause lactic acidosis in renal impairment.

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Adela

4 months ago

Alright, let's see. Metformin can cause lactic acidosis, which is a serious complication, especially in patients with impaired kidney function. I'm pretty confident that's the right answer here.

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Dustin

5 months ago

Okay, let me see here. The question is asking about the reason for holding metformin in patients with reduced renal function. I think the key here is to focus on the potential side effects of metformin in that context.

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Pura

5 months ago

Hmm, this looks like a pretty complex case with a lot of different medications and medical conditions. I'll need to carefully review the information and think through the potential reasons for holding metformin.

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