Related Experiment Video
Updated: Feb 15, 2026
Assessment of Vascular Function in Patients With Chronic Kidney Disease
Published on: June 16, 2014
Evaluation of Serum Symmetric Dimethylarginine Concentration as a Marker for Masked Chronic Kidney Disease in Cats
M E Peterson1,2, F V Varela1, M Rishniw2,3
1Animal Endocrine Clinic , New York, NY.
Insights
Serum symmetric dimethylarginine (SDMA) can help predict azotemic chronic kidney disease (CKD) in hyperthyroid cats. While highly specific, SDMA has low sensitivity for identifying masked azotemia before treatment.
Area of Science:
- Veterinary Medicine
- Nephrology
- Endocrinology
Background:
- Hyperthyroidism can mask chronic kidney disease (CKD) in cats by altering kidney function markers.
- Current diagnostic methods lack reliability in predicting azotemic CKD in hyperthyroid cats post-treatment.
Purpose of the Study:
- To evaluate serum symmetric dimethylarginine (SDMA) as a predictive marker for masked azotemia in hyperthyroid cats.
- To assess the diagnostic accuracy of SDMA in identifying cats with pre-azotemic CKD.
Main Methods:
- A prospective study involving 262 hyperthyroid cats and 206 healthy controls.
- Measurement of creatinine, urea nitrogen, SDMA, T4, and TSH before and after radioiodine (131I) treatment.
- Azotemia classification based on post-treatment creatinine levels (>2.1 mg/dL).
Main Results:
- 16% of hyperthyroid cats developed azotemia post-treatment.
- Pre-treatment SDMA was elevated in 14 of the 42 cats that became azotemic.
- SDMA demonstrated 33.3% sensitivity and 97.7% specificity for predicting pre-azotemic CKD.
Conclusions:
- Elevated serum SDMA in hyperthyroid cats can indicate a risk of developing azotemia after treatment.
- SDMA offers high specificity but limited sensitivity for detecting masked azotemic CKD in this population.
Background:
Hyperthyroidism can complicate (mask) the diagnosis of chronic kidney disease (CKD) because it increases glomerular filtration rate and decreases body muscle mass, both of which can lower serum creatinine concentrations. Currently, there is no clinical test that can reliably predict which hyperthyroid cats have concurrent azotemic CKD that will become apparent after treatment of the hyperthyroidism.
Objectives:
To investigate serum symmetric dimethylarginine (SDMA) concentration as a potential marker of masked azotemia in untreated hyperthyroid cats.
Animals:
Two hundred and sixty-two hyperthyroid cats and 206 aged-matched, clinically normal cats.
Methods:
Prospective study. We measured creatinine, urea nitrogen, SDMA, T4 , and TSH concentrations before and 1, 3, and 6 months after treatment with radioiodine (131 I) and classified 131 I-treated cats as azotemic or nonazotemic based on persistent, post-treatment creatinine concentrations >2.1 mg/dL. Groups were compared via nonparametric tests, and diagnostic accuracy was determined by receiver operating characteristic analysis and logistic regression.
Results:
No hyperthyroid cats were azotemic before treatment, but 42 (16%) became azotemic when rechecked at 4-8 months (median, 6 months) after 131 I treatment; of these, 14 had high SDMA concentrations before treatment. As a diagnostic test for pre-azotemic (masked) CKD in untreated hyperthyroid cats, SDMA showed a sensitivity of 33.3% and specificity of 97.7%.
Conclusions And Clinical Importance:
Finding a high serum SDMA concentration in a hyperthyroid cat can help predict development of azotemia after treatment. The test has high diagnostic test specificity (few false-positive results) but relatively low sensitivity (fails to predict azotemia in most hyperthyroid cats).
Related Concept Videos
01:25Chronic Kidney Disease I: Introduction
01:24Chronic Kidney Disease II: Clinical Manifestations
01:28Chronic Kidney Disease III: Interprofessional Care
01:18Chronic Kidney Disease IV: Nursing Management
01:25Drug Dosing in Renal Diseases: Measurement of Serum Creatinine Concentration and Clearance
01:28Drug Dosing in Renal Diseases: Estimation of Glomerular Filtration Rate Based on Serum Creatinine Concentration