The study aims to present a case study of a patient with supratherapeutic serum gentamicin concentration. An 83-year-old male was admitted to the Department of Internal Medicine for persistent loss of appetite, decompensated heart failure, and pneumonia. He was treated with 240 mg gentamicin daily alongside ampicillin/sulbactam penicillin antibiotic. The trough gentamicin concentrations and estimated glomerular filtration rate from creatinine (eGFRcrea) and cystatin C (eGFRcys) were performed. The patient had the supratherapeutic trough gentamicin concentration of 2.5 mg/L. eGFRcrea was 62 mL/min/1.73m2 and eGFRcys was 25 mL/min/1.73m2. The difference between eGFRcrea and eGFRcys was 148%. Falsely high eGFRcrea in elderly patient led to the supratherapeutic gentamicin concentration even after the standard 240 mg gentamicin dose.

Department of Clinical Biochemistry and Pharmacology Tomas Bata Hospital in Zlín Zlín Czech Republic

Department of Clinical Pharmacy Tomas Bata Hospital in Zlín Zlín Czech Republic

Institute of Clinical Biochemistry and Diagnostics Medical Faculty in Hradec Králové Charles University Prague Prague Czech Republic

Zobrazit více v PubMed

Hodiamont CJ, van den Broek AK, de Vroom SL, Prins JM, Mathôt RAA, van Hest RM. Clinical Pharmacokinetics of Gentamicin in Various Patient Populations and Consequences for Optimal Dosing for Gram-Negative Infections: An Updated Review. Clin Pharmacokinet. 2022;61:1075–94. 10.1007/s40262-022-01143-0 PubMed DOI PMC

Cerezo I, Cancho B, Rodriguez Sabillon JA, Jorge A, Alvarez Lopez A, Valladares J, et al. Comparative Prognostic Value of Glomerular Filtration Rate, Serum Cystatin C, Beta-2-Microglobulin and Albuminuria for Death and Chronic Kidney Disease Progression. J Clin Lab Anal. 2025;39:e25139. 10.1002/jcla.25139 PubMed DOI PMC

Dodder NG, Tai SSC, Sniegoski LT, Zhang NF, Welch MJ. Certification of Creatinine in a Human Serum Reference Material by GC-MS and LC-MS. Clin Chem. 2007;53:1694–9. 10.1373/clinchem.2007.090027 PubMed DOI

Grubb A, Blirup-Jensen S, Lindström V, Schmidt C, Althaus H, Zegers I, et al. First certified reference material for cystatin C in human serum ERM-DA471/IFCC. Clin Chem Lab Med. 2010;48:1619–21. 10.1515/CCLM.2010.318 PubMed DOI

Levey AS, Stevens LA, Schmid CH, Zhang YL, Castro AF, 3rd, Feldman HI, et al. A new equation to estimate glomerular filtration rate. Ann Intern Med. 2009;150:604–12. 10.7326/0003-4819-150-9-200905050-00006 PubMed DOI PMC

Inker LA, Schmid CH, Tighiouart H, Eckfeldt JH, Feldman HI, Greene T, et al. Estimating Glomerular Filtration Rate from Serum Creatinine and Cystatin C. N Engl J Med. 2012;367:20–9. 10.1056/NEJMoa1114248 PubMed DOI PMC

Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group . KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105 4S:S117–314. 10.1016/j.kint.2023.10.018 PubMed DOI

Šálek T, Šálek T, Schneiderka P, Studená B, Votroubková M. Survey on request form content and result reporting in therapeutic drug monitoring service among laboratories in Czechia and Slovakia. Biochem Med (Zagreb). 2020;30:020706. 10.11613/BM.2020.020706 PubMed DOI PMC

Groothof D, Shehab NBN, Erler NS, Post A, Kremer D, Polinder-Bos HA, et al. Creatinine, cystatin C, muscle mass, and mortality: Findings from a primary and replication population-based cohort. J Cachexia Sarcopenia Muscle. 2024;15:1528–38. 10.1002/jcsm.13511 PubMed DOI PMC

Hanna PE, Wang Q, Strohbehn IA, Moreno D, Harden D, Ouyang T, et al. Medication-Related Adverse Events and Discordancies in Cystatin C–Based vs Serum Creatinine–Based Estimated Glomerular Filtration Rate in Patients With Cancer. JAMA Netw Open. 2023;6:e2321715. 10.1001/jamanetworkopen.2023.21715 PubMed DOI PMC

Rebollo N, Cepeda-Piorno FJ. Cystatin C for therapeutic drug monitoring. Clin Chem. 2015;61:804–7. 10.1373/clinchem.2014.225847 PubMed DOI

Chin PKL, Chew-Harris JSC, Florkowski CM, Begg EJ. The performance of contemporary cystatin C-based GFR equations in predicting gentamicin clearance. Br J Clin Pharmacol. 2015;79:268–77. 10.1111/bcp.12501 PubMed DOI PMC

Karimzadeh I, Abdollahpour-Alitappeh M, Ghaffari S, Mahi-Birjand M, Barkhordari A, Alemzadeh E. Aminoglycosides: Single- or Multiple-daily Dosing? An Updated Qualitative Systematic Review of Randomized Trials on Toxicity and Efficacy. Curr Mol Med. 2024;24:1358–73. 10.2174/1566524023666230801160452 PubMed DOI

Chen DC, Lu K, Scherzer R, Lees JS, Rutherford E, Mark PB, et al. Cystatin C- and Creatinine-based Estimated GFR Differences: Prevalence and Predictors in the UK Biobank. Kidney Med. 2024;6:100796. 10.1016/j.xkme.2024.100796 PubMed DOI PMC

Wang T, Zhu Y, Liu X, Zhang Y, Zhang Z, Wu J, et al. Cystatin C and sarcopenia index are associated with cardiovascular and all-cause death among adults in the United States. BMC Public Health. 2024;24:1972. 10.1186/s12889-024-19137-x PubMed DOI PMC

Šálek T, Vodička M, Gabrhelík T. Estimated glomerular filtration rate in patients overdosed with gentamicin. J Lab Med. 2020;44:35–9. 10.1515/labmed-2019-0124 DOI

Šálek T, Vodička M, Gřiva M. Cystatin C may be better than creatinine for digoxin dosing in older adults with atrial fibrillation. J Clin Lab Anal. 2020;34:e23427. 10.1002/jcla.23427 PubMed DOI PMC

Hu C, Zhang Z, Hou B, Xue H, Pu X, Ye J. Prognostic value of serum cystatin C in patients with sepsis. Indian J Pathol Microbiol. 2023;66:573–6. 10.4103/ijpm.ijpm_804_21 PubMed DOI

Hundemer GL, Sood MM, Akbari A. Beyond Creatinine: Is Cystatin C the New Global Standard for Estimated Glomerular Filtration Rate Evaluation? Kidney Med. 2024;6:100806. 10.1016/j.xkme.2024.100806 PubMed DOI PMC