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SDMA case study: Jimmy

Background information

Name: Jimmy
Age: 13 years
Breed: Domestic shorthair
Gender: Neutered male

Presenting reason
Jimmy was brought in for his annual wellness examination and vaccines.

History
He was an indoor/outdoor cat, and his owner reported that Jimmy seemed to be doing fine and that there were no current concerns.

Physical examination
Jimmy was bright, alert, and responsive (BAR). Normal temperature, pulse, and respiration rate were observed. He had good muscle mass and a good body condition score. Remainder of physical examination was unremarkable, except for some moderate periodontal disease.

Diagnostic plan

A dental cleaning was recommended, and samples were collected for a preanesthetic screen for complete blood count (CBC); chemistry panel, including the Catalyst SDMA and Total T4 Test Kit; and a complete urinalysis.

Diagnostic review

  • Noteworthy abnormalities found on Jimmy’s laboratory/diagnostic tests included an increased SDMA* of 23 μg/dL, and an inappropriate urine specific gravity of 1.015.
  • The balance of the diagnostics, including creatinine and total T4, were within normal limits.
  • SDMA is an earlier1 and more reliable2 biomarker for kidney function than creatinine and warrants follow-up investigation when increased.
     

Next steps

  • The owner was informed that some supportive care and follow-up were indicated for Jimmy ahead of his dental procedure.
  • Increased access to drinking water (bowl outside and on different levels inside the home), a diet designed for senior patients,3 and a recheck appointment in 2 weeks were recommended.
  • Other considerations included diagnostic imaging of the kidneys and associated structures and assessment of blood pressure, as well as a urine culture and MIC (minimum inhibitory concentration) susceptibility, urine protein:creatinine ratio (UPC), and updated retrovirus testing. 
     

Follow-up and diagnosis

  • Jimmy presented 1 month later and his laboratory work showed that SDMA remained increased but stable at 19 μg/dL and his urine specific gravity was unchanged at 1.015. The remainder of his laboratory results remained within reference intervals.
  • An abdominal ultrasound showed no evidence of urinary stones or infection. He had small kidneys, consistent with chronic kidney disease (CKD).
  • Systolic blood pressure was 175 mm Hg, which was persistently increased when Jimmy was rechecked a few days later.
  • With the results in hand, and following the International Renal Interest Society (IRIS) CKD Staging Guidelines, Jimmy was diagnosed with IRIS CKD Stage 2 disease. It was determined that Jimmy be placed on medication for his high blood pressure and that his owners switch him to a kidney therapeutic diet while continuing to provide him several fresh water sources.

Patient reports

Chemistry

IDEXX SDMA report screenshot for Jimmy case study

Total T4

Endocrinology report screenshot for Jimmy case study

Urinalysis

Urinalysis reports screenshot for Jimmy case study

Hematology

Hematology report screenshot for Jimmy case study

IRIS CKD staging guidelines

Stage of kidney disease infographic for Jimmy case study

Discussion

Cases like Jimmy’s are common for general practitioners, and his case reinforces that even a single increase in SDMA warrants further investigation and possible management. 

SDMA detects problems sooner,1 and it is more reliable2 than creatinine in assessing kidney function. SDMA also helps identify concurrent conditions, such as high blood pressure.4 

Making modest changes in Jimmy’s access to fresh water and instituting a kidney-therapeutic diet might slow the progression of Jimmy’s kidney disease. Jimmy’s kidney disease was able to be appropriately monitored and managed prior to his dental procedure. During his dental procedure, additional precautions were also taken to protect his kidneys. Longer-term regular appointments can be scheduled to monitor his kidney disease more closely thanks to the early detection afforded by SDMA. This will allow for earlier identification and treatment of kidney disease progression and complicating conditions. 

*Symmetric dimethylarginine.

References

  1. Hall JA, Yerramilli M, Obare E, Yerramilli M, Jewell DE. Comparison of serum concentrations of symmetric dimethylarginine and creatinine as kidney function biomarkers in cats with chronic kidney disease. J Vet Intern Med. 2014;28(6):1676–1683.
  2. Hall JA, Yerramilli M, Obare E, Yerramilli M, Yu S, Jewell DE. Comparison of serum concentrations of symmetric dimethylarginine and creatinine as kidney function biomarkers in healthy geriatric cats fed reduced protein foods enriched with fish oil, L-carnitine, and medium-chain triglycerides. Vet J. 2014;202(3):588–596.
  3. Hall JA, MacLeay J, Yerramilli M, et al. Positive impact of nutritional interventions on serum symmetric dimethylarginine and creatinine concentrations in client-owned geriatric cats. PLoS One. 2016;11(4):e0153654.
  4. Acierno MJ, Brown S, Coleman AE, et al. ACVIM consensus statement: Guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats. J Vet Intern Med. 2018;32(6):1803-1822.