It is recommended to monitor complete blood count in patients on chronic metformin because of what reason?

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. lock­out 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.

It is recommended to monitor complete blood count in patients on chronic metformin because of what reason?

A. Metformin may decrease erythropoietin level

B. Metformin may decrease platelet count

C. Metformin may decrease vitamin B12 levels

D. Metformin may cause leukocytosis

E. Metformin may decrease iron absorption

View Answer

Answer: C

Explanation:

Metformin may impair the absorption of vitamin B12, especially in those with inadequate vitamin b12 or calcium intake/absorption. Vitamin b12 deficiency can be treated with discontinuation of therapy or supplementation. Vitamin b12 serum concentrations should be monitored periodically with long-term therapy.