Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Mar;35(2):493-503.
doi: 10.1007/s40620-021-01122-x. Epub 2021 Aug 5.

Estimation of kidney function in patients with primary neuromuscular diseases: is serum cystatin C a better marker of kidney function than creatinine?

Annika Aldenbratt  1 , Christopher Lindberg  2 , Elias Johannesson  3 , Ola Hammarsten  4 , Maria K Svensson  5
Affiliations

Estimation of kidney function in patients with primary neuromuscular diseases: is serum cystatin C a better marker of kidney function than creatinine?

Annika Aldenbratt et al. J Nephrol. 2022 Mar.

Abstract

Background: Using serum creatinine leads to an overestimation of kidney function in patients with primary neuromuscular disorders, and reduced kidney function may remain undetected. Cystatin C (CysC) could provide a better estimation.

Aim: To evaluate the precision, accuracy, and bias of two creatinine-, one cystatin C-based and one combined equation to estimate glomerular filtration rate (eGFR) in patients with primary neuromuscular disease.

Patients and methods: Of the 418 patients initially identified at the out-patient clinic, data on kidney function was obtained for 145 adult patients (age 46 ± 14 years, BMI 26 ± 6 kg/m2) with primary neuromuscular disease. Kidney function was measured by iohexol clearance, and blood samples for serum creatinine and CysC were drawn simultaneously. Bias was defined as the mean difference between eGFR and measured iohexol clearance, and accuracy as the proportion of eGFRs within ± 10% (P10) of measured clearance.

Results: Kidney function (iohexol clearance) was 81 ± 19 (38-134) ml/min/1.73m2. All equations overestimated kidney function by 22-60 ml/min/1.73m2. eGFR CysC had the lowest bias overall 22 (95% CI 20-26) ml/min/1.73m2 also at all levels of kidney function we evaluated (at 30-59 ml/min/1.73m2 bias was 27 (95% CI 21-35), at 60-89 it was 25 (95% CI 20-28) and at ≥ 90 it was 12 (95% CI 7-22)). eGFR CysC also had the best accuracy in patients with reduced kidney function (P10 was 5.9% at 30-59 ml/min/1.73m2).

Conclusions: Cystatin C-based estimations of kidney function performed better than creatinine-based ones in patients with primary neuromuscular disease, but most importantly, all evaluated equations overestimated kidney function, especially in patients with reduced kidney function. Therefore, kidney function should be measured by gold-standard methods when precision and accuracy are needed.

Keywords: Creatinine; Cystatin C; Estimated GFR; Iohexol clearance; Muscle mass; Neuromuscular disease.

PubMed Disclaimer

Conflict of interest statement

None of the authors has any conflict of interest or competing interests to declare.

Figures

Fig. 1
Fig. 1
A flowchart of the recruitment of study participants
Fig. 2
Fig. 2
a Bland–Altman-plots of the differences between estimated GFR (eGFR Cys C) and measured iohexol clearance. Kidney function (measured clearance) levels as indicated; 38–59, 60–89 and ≥ 90 ml/min/1.73m2. b Bland–Altman-plots of the differences between estimated GFR (eGFR CKD-EPI) and measured clearance. Kidney function (measured clearance) levels as indicated; 38–59, 60–89 and ≥ 90 ml/min/1.73m2. c Bland–Altman-plots of the differences between (eGFR CysC + CKD-EPI) and measured iohexol clearance. Kidney function (measured clearance) levels as indicated; 38–59, 60–89 and ≥ 90 ml/min/1.73m2. d Bland–Altman-plots of differences between (eGFR MDRD) and measured iohexol clearance. Kidney function (measured clearance) levels as indicated; 38–59, 60–89 and ≥ 90 ml/min/1.73m2.GFR measured iohexol clearance
See this image and copyright information in PMC

References

    1. Perrone RD, Madias NE, Levey AS. Serum creatinine as an index of renal function: new insights into old concepts. Clin Chem. 1992;38(10):1933–1953. doi: 10.1093/clinchem/38.10.1933. - DOI - PubMed
    1. Levey AS, Coresh J, Balk E, Kausz AT, Levin A, Steffes MW, Hogg RJ, Perrone RD, Lau J, Eknoyan G, National Kidney F. National Kidney Foundation practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Ann Intern Med. 2003;139(2):137–147. doi: 10.7326/0003-4819-139-2-200307150-00013. - DOI - PubMed
    1. Stevens PE, Levin A, Kidney Disease: Improving Global Outcomes Chronic Kidney Disease Guideline Development Work Group M Evaluation and management of chronic kidney disease: synopsis of the kidney disease: improving global outcomes 2012 clinical practice guideline. Ann Intern Med. 2013;158(11):825–830. doi: 10.7326/0003-4819-158-11-201306040-00007. - DOI - PubMed
    1. Current Chronic Kidney Disease (CKD) nomenclature used by KDIGO (2020). Transplantation 104 (4S1 Suppl 1):7. 10.1097/01.tp.0000660604.20951.09 - PubMed
    1. Griggs RC, Forbes G, Moxley RT, Herr BE. The assessment of muscle mass in progressive neuromuscular disease. Neurology. 1983;33(2):158–165. doi: 10.1212/wnl.33.2.158. - DOI - PubMed

LinkOut - more resources