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Category: Feline Health

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10/02/2025
ecallenFeline HealthTRUFORMA

Diagnosing Feline Hyperthyroidism: Why the TRUFORMA® Biosensor Testing Platform’s Feline TSH Test Outperforms Traditional Methods 

Based on the continuing education webinar presented by Dr. Kristin Marzin, DVM* 

Feline hyperthyroidism affects 10% of geriatric cats, making it the most common endocrine disorder in veterinary medicine. Yet for many practitioners, diagnosing borderline cases remains frustratingly difficult. Does this scenario sound familiar? You have a 12-year-old cat with weight loss and a palpable thyroid nodule, but the T4 comes back normal. Do you treat? Wait and retest? Send out for more diagnostics and wait days for results? 

Traditional testing methods leave veterinarians in diagnostic gray zones far too often—and waiting for send-out labs delays treatment decisions. The TRUFORMA® platform’s feline-specific TSH test changes that, offering the sensitivity and specificity needed to confidently diagnose hyperthyroidism in 20 minutes, right in your clinic. 

The Problem: Total T4 Testing Misses Up to 10% of Hyperthyroid Cats

While approximately 90% of hyperthyroid cats can be diagnosed through clinical signs and elevated T4, a significant percentage of cases fall into diagnostic gray zones. Several factors complicate diagnosis: 

  • Early disease stages where T4 values haven’t elevated yet 
  • Normal T4 fluctuations that may drift in and out of reference ranges 
  • Non-thyroidal illness that can suppress T4 values into normal ranges 

The 2016 AAFP guidelines for hyperthyroid management organize these challenging cases into six categories, with most requiring either repeated T4 testing or additional thyroid hormone testing to confirm or exclude hyperthyroidism. 

Why Free T4 Falls Short in Real-World Practice

Traditionally, free T4 (measured by equilibrium dialysis) has been used to support hyperthyroid diagnosis in cats, offering nearly 99% sensitivity. However, this highly sensitive test has limitations: 

  • Free T4 can be normal, increased, or decreased in cats with non-thyroidal illness 
  • Should not be used as the sole confirmatory test 
  • Newer chemiluminescent methods show questionable accuracy, consistently undervaluing results compared to equilibrium dialysis 
  • Not recommended for monitoring cats following radioactive iodine therapy 

Feline TSH vs. Canine TSH: Why Species-Specific Testing Matters

In hyperthyroid cats, autonomously secreted thyroid hormones suppress TSH production to near-zero levels—a finding that should make TSH testing ideal for diagnosis. The problem? Canine TSH assays weren’t designed for feline physiology. 

  • Normal feline TSH range is often lower than the canine assay’s lower limit of quantification 
  • Canine TSH cannot reliably differentiate between healthy cats and those with non-thyroidal illness 
  • Cannot be used as a sole diagnostic test 

Despite these limitations, research by Dr. Mark Peterson’s group examining 917 hyperthyroid cats demonstrated that serum TSH concentrations are suppressed in 98% of hyperthyroid cats, with median TSH below 0.03 ng/mL compared to 0.05 ng/mL in clinically normal cats. The study found that only 2% of hyperthyroid cats had measurable canine TSH concentrations, while nearly 70% of euthyroid cats had detectable levels. This meant that finding a measurable canine TSH could help rule out hyperthyroidism in cats, though the test showed poor specificity (69.9%) when used alone. 

The key insight: while canine TSH could be somewhat useful for screening, its lack of sensitivity in the low range where feline values typically fall—combined with poor specificity—highlighted the critical need for a feline-optimized assay. 

How the TRUFORMA® Platform's Feline TSH Test Solves the Diagnostic Puzzle

Zomedica developed the TRUFORMA biosensor testing platform’s feline-verified TSH test to address every limitation of canine assays—with technology optimized specifically for feline physiology and delivered through the only in-clinic platform available. Here’s what makes the TRUFORMA® platform test different: 

The Only In-Clinic Feline TSH Test Available

The TRUFORMA system is the only point-of-care platform offering feline-specific TSH testing. Get accurate results in 20 minutes—no send-outs, no waiting, no delayed treatment decisions. Diagnose and create treatment plans in the same appointment, improving both patient outcomes and client satisfaction. 

3X More Sensitive Than Canine TSH

The TRUFORMA platform’s feline TSH test has a lower limit of detection of 0.008 ng/mL compared to 0.03 ng/mL for canine TSH—providing the precision needed to accurately measure feline TSH values in the critical low range where feline physiology operates. 

Prevents Misdiagnosis in 12% of Healthy Cats

TRUFORMA platform test clinical data from 170 feline samples revealed: 

  • 95% of healthy cats had serum TSH above 0.01 ng/mL
  • 93% of hyperthyroid cats had TSH below 0.01 ng/mL 
  • 12% of normal cats tested below the canine assay’s detection limit but had measurable TSH with the TRUFORMA platform test—preventing false positive diagnoses and unnecessary treatment 

Proven Precision You Can Trust

The TRUFORMA platform’s multi-instrument testing showed coefficient of variation less than 10%—2.5X better than industry standards—ensuring consistent, reliable results. 

Critical Application: Detecting Iatrogenic Hypothyroidism

Here’s a sobering statistic: Nearly 50% of treated hyperthyroid cats develop iatrogenic hypothyroidism, regardless of treatment method. Even more concerning? T4 monitoring alone misses almost 80% of these cases. 

Why does this matter for your patients? 

  • Decreased GFR and progression to azotemic chronic kidney disease 
  • 50% shorter median survival time in cats that become azotemic 
  • Subtle clinical signs easily missed or attributed to aging 

The solution: The TRUFORMA  platform’s T4 test and feline TSH test combination identifies these cases early. When you see low or low-normal T4 with elevated TSH, you can adjust methimazole doses or add thyroid supplementation before kidney damage progresses—all with same-day results that enable immediate intervention. 

Catching Hyperthyroidism Earlier: The TRUFORMA Platform Advantage

Traditional send-out testing often catches hyperthyroidism only after significant organ damage has occurred—and delays treatment by days while you wait for results. The TRUFORMA biosensor testing platform changes this timeline by identifying cats in the earliest disease stages with same-appointment results, enabling intervention when it’s most effective and before irreversible complications develop. 

Early detection means: 

  • Prevention of cardiac remodeling and hypertension 
  • Reduced risk of kidney damage from hyperfiltration 
  • Better treatment outcomes with less aggressive intervention 
  • Improved quality of life for your feline patients 

The Research Behind the TRUFORMA Platform's Feline TSH Test

Recent peer-reviewed research published by Dr. Mark Peterson compared the TRUFORMA platform’s feline-optimized TSH assay with chemiluminescent canine TSH testing across multiple patient populations: hyperthyroid cats, radioiodine-treated cats, chronic kidney disease patients, and healthy cats. 

The verdict? The TRUFORMA platform’s feline-specific test demonstrated superior sensitivity and specificity across all groups, offering a more practical alternative to thyroid scintigraphy for practices without nuclear medicine capabilities—with the critical advantage of in-clinic results in 20 minutes. 

Implementing The TRUFORMA Biosensor Testing Platform in Your Practice

The TRUFORMA platform’s T4 + feline TSH is becoming the new diagnostic standard, replacing the T4/free T4 send-out combination for hyperthyroid workup. The TRUFORMA in-clinic biosensor testing platform offers value across your entire case management workflow: 

✓ Initial diagnosis of suspected hyperthyroidism—results in 20 minutes 

 ✓ Routine wellness screening in geriatric cats during annual exams 

 ✓ Treatment monitoring to prevent iatrogenic hypothyroidism 

 ✓ Differentiating subclinical hyperthyroidism from non-thyroidal illness 

Same-day diagnosis means same-day treatment decisions—improving patient outcomes, increasing client satisfaction, and eliminating the frustration of waiting for send-out results while your patient continues to deteriorate. 

Ready to bring same-day feline hyperthyroid diagnosis to your practice? The TRUFORMA in-clinic biosensor testing platform is the only point-of-care system offering feline-specific TSH testing. Get accurate results in 20 minutes and make confident treatment decisions in the same appointment.

Discover TRUFORMA System Testing Solutions

*Dr. Marzin is a Zomedica Professional Services Veterinarian and was paid for this presentation. Watch the full presentation here.

© 2025 Zomedica Inc. All rights reserved. TRUFORMA is a registered trademark of Zomedica Inc. 

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04/06/2025
ecallenFeline HealthTRUFORMA

How TRUFORMA’s Feline-Optimized TSH Test Prevented Unnecessary Treatment

A Case Study by Kristin Marzin, DVM

Accurate thyroid testing is crucial for feline health, but traditional methods can sometimes lead to misdiagnosis. This case study highlights how TRUFORMA’s innovative feline-optimized TSH test played a pivotal role in preventing unnecessary treatment and ensuring proper patient care. 

History and Physical Examination Findings

At the Oregon Veterinary Specialty Hospital’s Feline Radioiodine Center, a neutered 6-year-old male domestic shorthair feline presents with suspected hyperthyroidism. Upon examination, the patient was noted to be overweight, with a body condition score (BCS) of 7/9. They have also gained weight over the past couple of years. While at the time of the first visit the patient is asymptomatic, they have a history of: 

  • Emergency room visit two years prior for hypersalivation, agitation, and polydipsia 
  • Elevated total T4 (5.0 mcg/dl) found at ER visit 
  • Persistent elevation of total T4 in subsequent wellness visits 

The patient’s littermate had the same presentation to the ER and bloodwork also indicated a T4 elevation, but he had additional signs of hyperthyroidism and therefore was treated with methimazole. Considering the mild starting total T4 value, higher doses than expected of methimazole were required to lower the normal range by the primary veterinarian. The littermate was then treated with I131, but there was concern that this may not have been curative, as total T4 improved but remained elevated despite positive clinical response. Scintigraphy is not available in the state of Oregon and could not be pursued for either patient. 

Diagnostic Findings and Interpretation

At the time of the ER visit, the only abnormal lab finding for the patient was elevated total T4 (5.0 mcg/dl, reference range 0.8-4.7 mcg/dl).  

At subsequent visits in the next couple of years, the T4 remained slightly elevated at 4.8 mcg/dl and 4.4 mcg/dl (reference range 0.8-4.0 mcg/dl). At one of these time points (total T4 4.4 mcg/dl), the free T4 measured >100 (reference range 10-50). The patient gained weight and maintained an overweight body condition after the ER visit. At these visits, there were no other significant laboratory findings. 

Thyroid Testing at the Feline Radioiodine Center

On presentation to Dr. Decker, additional thyroid testing was performed.  

  • Total T4 remained elevated at 5.7 mg/dl (reference range 0.8-4.4 mcg/dl).  
  • A feline-optimized TSH performed using the TRUFORMA Diagnostic System was within normal limits at 0.016 ng/ml (reference range 0.01-0.3 ng/ml).  
  • A free T4, T3, and chemiluminescent canine TSH were also all within normal limits.

Expert Interpretation of Feline Thyroid Test Results

With the patient’s lack of clinical signs and all laboratory testing other than total T4 showing normal results, it was suggested that the patient’s elevation in total T4 was either spurious or normal for this patient. Since the patient had such a long history of reliably high total T4 values, Dr. Decker concluded that the elevation in T4 was likely a normal variation for this patient, and he was not diagnosed as hyperthyroid. Since the patient’s littermate had exhibited similar lab work and did not respond well to medical management for hyperthyroidism, it was suggested that this could be an inherited anomaly. 

Treatment and Outcome

No treatment was initiated for this patient. Dr. Decker recommended the patient return for routine thyroid monitoring every 6-12 months, or sooner if clinical signs develop. Thyroid monitoring tests would include a total T4, feline-optimized TSH, T3, and free T4.  

“It is important to treat the cat and not just the number, but be sure you are getting the best numbers possible,” Dr. Decker stated upon conclusion of this case. This can be achieved by thorough thyroid testing, which should include TRUFORMA’s feline-optimized TSH assay. 

Reflecting on a Complex Thyroid Case

This case shows the importance of thyroid testing in cats beyond just a total T4. Initiating therapy for hyperthyroidism in this case could have had potentially dangerous effects for the patient since he is not truly hyperthyroid. A feline-optimized TSH, only able to be performed on the TRUFORMA system, helped Dr. Decker reach the appropriate diagnosis and clinical decision for this patient, and will allow her to monitor him closely in the event he truly becomes hyperthyroid.  

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07/29/2024
ecallenFeline HealthTRUFORMA

Revolutionizing Feline Thyroid Care: The Importance of the TRUFORMA® Exclusive TSH Test for Cats

Hyperthyroidism in cats can be one of the simpler diagnoses made by veterinarians. When a geriatric cat is showing signs of weight loss, increased appetite, and hyperactivity, the veterinarian simply needs to test for elevated T4 levels to confirm that the patient is hyperthyroid. But what happens when the disease is not as straightforward?  

Understanding Feline Hyperthyroidism

It is common for older cats to have concurrent illnesses such as renal disease, cancer, or enteropathy. Non-thyroidal illness can also artificially decrease T4 levels. In fact, 10% of hyperthyroid cats and more than 30% of cats with early thyroid disease will have a normal T4.  In these cases, further diagnostics should be performed to obtain a definitive diagnosis. 

The Role of TSH in Thyroid Diagnostics

TSH is the most utilized hormone for diagnosis of thyroid disease in humans but is not as widely performed in veterinary medicine. However, this hormone can give us a lot of information about the status of thyroid function. Due to the negative feedback mechanism of the body, decreased concentrations of TSH indicate that there is an excess of circulating thyroid hormone. Theoretically, TSH could be a great confirmatory test for hyperthyroidism in cats, because it allows us to look at the function of the feedback loop. Historically, the only option for testing TSH has been a chemiluminescent canine assay that can only measure TSH values as low as 0.03 ng/mL. Studies have shown that while cats with undetectable TSH are more likely to be diagnosed as hyperthyroid within a couple years, there are some normal cats with TSH levels lower than 0.03 ng/mL. Therefore, current TSH testing lacks some specificity for diagnosing the disease.

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Feline-Optimized TSH Enhances Patient Care

The TRUFORMA In-Clinic Biosensor Testing Platform offers the first and only feline-optimized TSH, changing how we can diagnose and monitor thyroid disease in cats. Using Bulk Acoustic Wave (BAW) technology, TRUFORMA’s feline optimized TSH assay achieves a lower limit of quantification (LLOQ) far below the chemiluminescent assay, at 0.008 ng/mL. This makes TRUFORMA’s assaymore sensitive and specific for diagnosis of hyperthyroidism and thus allows veterinarians to better distinguish between normal cats and hyperthyroid cats. In cats with borderline elevated or high-normal T4 levels due to non-thyroidal illness or early disease, feline-optimized TSH is an excellent confirmatory test. 

Validating TRUFORMA's Feline-Optimized TSH Assay

A 2024 study performed by Dr. Mark Peterson, a leading veterinary endocrinology specialist, validates and compares the TRUFORMA feline-optimized TSH assay to the traditional chemiluminescent method used at reference laboratories. It found that because of the very low values that the TRUFORMA assay can detect, veterinarians can diagnose hyperthyroidism earlier in the disease process as well as in cases of subclinical disease. This can lead to the patient receiving treatment sooner, before much of the damage to other body systems occurs. 

Screening and Early Detection

TRUFORMA’s feline-optimized TSH assay can also be used as a routine screening test for geriatric felines, the same way we often screen for T4 in these patients. One study found that TSH levels less than 0.03 ng/ml were associated with an increased likelihood of hyperthyroid diagnosis within 14 months. This suggests the assay can be used as a biomarker to determine future risk of disease. 

Monitoring Hyperthyroidism Using Feline-Optimized TSH

Screening for and definitively diagnosing hyperthyroidism are not the only utilizations of the TRUFORMA TSH assay. Cats undergoing treatment for hyperthyroidism are at risk of developing iatrogenic hypothyroidism, which can cause a decline in renal function. An elevated TSH in these patients indicates that circulating thyroid hormone levels are too low, and a dosage adjustment or hormone supplementation is needed. 

Treating Hyperthyroidism Using Feline-Optimized TSH and Radioactive Iodine

It has also been suggested that TSH testing should be performed prior to administration of radioactive iodine as a treatment for hyperthyroidism. TSH levels greater than 0.03 ng/ml can indicate that the patient is more at risk of developing iatrogenic hypothyroidism after I131 therapy. It is recommended to wait to treat these patients until TSH levels have decreased below 0.03 ng/ml. If that is not possible, they should receive a lower dose of I131.

The Future is Bright with TRUFORMA’s Feline-Optimized TSH Assay

Every veterinarian has heard the adage “cats are not small dogs”. Having access to TRUFORMA’s feline-optimized TSH assay gives vets a better way to screen, diagnose, and monitor cats with hyperthyroidism – the most common endocrinopathy of the feline population. By diagnosing these patients sooner and being able to monitor their therapy closer, we can improve the quality of life for cats and their owners. 

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feline hyperthyroidism
11/20/2023
brianDiagnosticsFeline HealthTRUFORMA

How TRUFORMA Improves Feline Hyperthyroidism Detection: A Game-Changer for Veterinary Diagnostics

Feline hyperthyroidism is a common endocrine disorder in cats, but diagnosing it accurately has often been a challenge. Traditionally, testing methods for feline hyperthyroidism relied on canine reference ranges, which may not provide precise results for our feline friends. However, with the advent of TRUFORMA, a cutting-edge diagnostic system, veterinarians now have access to the first and only feline-optimized TSH assay, a game-changer in the diagnosis of this condition.

Understanding Feline Hyperthyroidism

Feline hyperthyroidism is a condition characterized by the overproduction of thyroid hormones, primarily thyroxine (T4), by the thyroid gland. This excess of thyroid hormones can lead to a range of symptoms including weight loss, increased appetite, restlessness, and hyperactivity. It is crucial to diagnose hyperthyroidism accurately and early, as untreated cases can lead to severe complications, including heart disease and kidney problems.

The History of Feline Hyperthyroidism Testing

The history of diagnosing feline hyperthyroidism has not been without its challenges. Many traditional tests were designed using canine reference ranges, which are not always applicable to cats. This can result in inaccurate diagnoses and unnecessary confusion for veterinarians. The need for a more precise and cat-specific approach has been a long-standing concern.

TRUFORMA: A New Era in Feline Hyperthyroidism Diagnosis

TRUFORMA is a diagnostic platform that leverages bulk acoustic wave (BAW) sensor technology to provide highly precise and sensitive measurements, surpassing the capabilities of optical-based diagnostic methods. This innovative system is changing the game in diagnosing complex thyroid and adrenal conditions.

The Feline-Optimized TSH Assay

One of TRUFORMA’s standout features is its feline optimized TSH assay, which has transformed the diagnosis of feline hyperthyroidism. Here’s why this assay is a game-changer:

Early Detection: With TRUFORMA, veterinarians can proactively create a thyroid profile in healthy adult cats between 5-8 years of age, making it easier to spot the onset of hyperthyroidism.

Diagnosing Earlier: TRUFORMA can identify early to mild hyperthyroidism in 10-40% of cats that may have normal T4 levels, allowing for swifter intervention and better outcomes.

Iatrogenic Hypothyroidism (IH) Monitoring: TRUFORMA’s TSH assay excels at differentiating iatrogenic hypothyroidism (a condition caused by treatment) from chronic kidney disease (CKD), even in cases where age and non-thyroidal illness do not affect TSH levels.

Wide Dynamic Range: The feline optimized TSH assay accurately measures the very low normal concentrations expected for cats, a range that other commercial TSH assays may not capture, ensuring a more precise diagnosis.

A More Confident Diagnosis

With TRUFORMA’s feline optimized TSH assay, veterinarians can diagnose feline hyperthyroidism with confidence and accuracy. This breakthrough technology, combined with the convenience of in-clinic testing, empowers veterinarians to provide the best care for their feline patients.

TRUFORMA’s feline optimized TSH assay is a significant milestone in the diagnosis of feline hyperthyroidism. It not only allows for earlier detection but also ensures a more accurate and cat-specific approach to testing. With this innovative technology at their disposal, veterinarians can confidently and efficiently diagnose feline hyperthyroidism, improving the health and well-being of their feline patients.
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