If the T4 level is high normal or borderline, the measurement should be repeated after concurrent diseases have been treated or after a period of 4 to 8 weeks, because hyperthyroidism is a chronic progressive disease and T4 levels increase over time. This is especially helpful for smaller nodules. Research indicates that there has been a change in emphasis from simply confirming a diagnosis in a cat presenting with classical clinical signs to diagnosing hyperthyroidism in cats with no clinical signs (Graves, 2017). We can also help you find other free or low-cost resources available. The use of a serum biochemistry profile allows your veterinarian to measure these components of serum and provides specific values for enzymes related to the liver, kidneys and pancreas, in addition to an evaluation of the electrolyte components of a serum sample, such as sodium and potassium. Peterson and Gamble (1990) found no difference in T4 levels between young and old cats, whereas a study carried out by Thoday and colleagues (1984) showed that both T4 and T3 varied with age. Many hyperthyroid cats have increases in the kidney related parameters (blood urea nitrogen [BUN] and creatinine). The same external laboratory was used each time. The mean T3 value was 0.46 0.08 nmol/L; within this age range, T3 values appeared to reach a plateau at this lower level after the initial decrease. Further studies are required to advance the level of knowledge in risk factors of the disease however Peterson (2012) suggested measures to help minimise the risk of hyperthyroidism. The pathogenesis of feline hyperthyroidism is poorly understood. Affiliate of Mars Inc. 2023 | Copyright VCA Canada Hospitals all rights reserved. Trepanier (2007) described that the best management options for hyperthyroidism, included radioiodine therapy, thyroidectomy or medical treatment with drugs that inhibit synthesis of thyroid hormone in the thyroid gland such as methimazole/thiamazole (Figure 2). More veterinary practitioners have improved their resources and are now able to run inhouse blood tests that previously would have been sent to an external laboratory. Free thyroxine concentration (fT4) is the portion of the thyroxine hormone that is not bound to any blood proteins. It is very common in older cats and most cases can be treated successfully. Thyroid Function in Cats | College of Veterinary Medicine at MSU Davidge-Pitts CJ and Thompson GB. Thyroid Hormone Testing in Cats | VCA Canada Animal Hospitals One way to raise TSH levels without withholding thyroid hormone is to give an injectable form of thyrotropin (Thyrogen) before the scan. Become a volunteer, make a tax-deductible donation, or participate in a fundraising event to help us save lives. Whether you want to learn about treatment options, get advice on coping with side effects, or have questions about health insurance, were here to help. The male cats (neutered) had significantly higher T4 values compared with the female cats (entire); the mean values were 41.9 7.6 nmol/L and 37.7 6.2 nmol/L, respectively. From all the purebreed cats analysed, 20 (62.5%) had elevated T4 results compared to 56 (32.9%) which were crossbreeds. In bilateral cases, both thyroid glands are affected, although one may be more affected than the other (Peterson, 2012). The relationship between coat colour and both hyperthyroidism and T4 result is summarised in Table 3. Conclusion: Symptoms can include an increase in appetite, weight loss and a poor coat. Diagnosing Hyperthyroidism in Cats (T3 & T4 Tests) - Cat-World However, significant daily variations have been shown to occur in T4 concentration in hyperthyroid cats, and in occasional cases the level may at times fall within the normal range (Peterson et al, 1987; Broome et al, 1988). The median T4 result was 45 nmol/litre with a range between 8153 nmol/litre as seen in Figure 3. If you are going to have surgery to treat thyroid cancer, a procedure called a laryngoscopy will probably be done first to see if the vocal cords are moving normally. In general, the thyroid hormones Diagnosis and treatment could therefore be valuable even in subclinical cats. Recent recommendations in feline cardiac care suggest not to treat cardiac problems unless the patient is in heart failure, has an atrial thromboembolism (ATE) episode or has enlarged left atria with spontaneous echo contrast (Sangster et al, 2014). They are also often used in people who have already been diagnosed with differentiated (papillary, follicular, or Hrthle cell) thyroid cancer to help show if it has spread. The range of T4 results in crossbreeds was between 8153 nmol/litre whereas purebreeds had a range between 25103 nmol/litre. Similarly, the most common crossbreed cat (DSH) was found to have a much lower prevalence of hyperthyroidism than cats categorised as other (i.e. A study conducted by Blois et al (2010) found that 1.85.5% of cats diagnosed with hyperthyroidism also had diabetes mellitus. 5th ed. Accessed at https://www.nccn.org/professionals/physician_gls/pdf/thyroid.pdf on May 12, 2020. The health parameters assessed for the 52 Waltham Centre cats used in the study investigating the effect of age on thyroid status indicated that all cats were clinically healthy. Scott-Moncrieff (2012) explained that cats with early hyperthyroidism or concurrent non-thyroidal illness may have a T4 concentration within the upper half of the reference range. Thyroid hormones have far-reaching effects on the body, in essence governing the body's metabolic rate. Each blood sample was taken from the jugular vein of each patient and decanted into a serum blood tube for analysis. Quantum Veterinary Diagnostics (2019) sets the range of normal serum T4 levels between 1348 nmol/litre. The tests commonly used are the measurement of thyroxine, which is often abbreviated as T4, and a T3 suppression test. WebSome cats may show no visible hyperthyroidism symptoms, which can make it difficult to diagnose in the first instance. Thyroid Blood Test: Types, Normal Levels, Analyzing Results These two parameters indicate how well the kidneys are filtering out metabolic waste products from the body. Hyperthyroidism is one of the most commonly diagnosed endocrine diseases affecting older cats (Wakeling et al, 2011; Graves, 2017). Feline Thyroid Tests | Cornell University College of Veterinary Below are some of the resources we provide. Cancer Information, Answers, and Hope. MRI scans are also very helpful in looking at the brain and spinal cord. Calcitonin is a hormone that helps control how the body uses calcium. The final nine categories of colour included (black, black and white, blue, brown, ginger, grey, tabby, tortoiseshell and white). Hyperthyroidism in cats: should we be routinely testing for early diagnosis? One problem using CT scans is that the CT contrast dye contains iodine, which interferes with radioiodine scans. Sign up to The Veterinary Nurse's regular newsletters and keep up-to-date with the very latest clinical research and CPD we publish each month. Although all the cats at Waltham Centre are virus free, these assays were carried out for the purpose of the completeness of the study. In most cases, diagnosing hyperthyroidism is straightforward: high levels of thyroid hormone in the bloodstream (total T4 or TT4) along with the typical signs. T3 levels exhibited an initial decrease to 5 y followed by a plateau. If applied to veterinary medicine it would emphasise the potential importance of treating those cats that do not show any clinical signs of hyperthyroidism yet suffer from the disease. Therefore, understanding those factors that have the potential to influence thyroid hormone levels is important in establishing normal values to which potentially hyperthyroid cats can be compared and in contributing to a more complete understanding of the aging cat. To examine the effect of age on serum thyroid hormone concentrations, a study was conducted only with cats from the Waltham Centre, thereby reducing possible environmental factors that might influence variability of results. You will be asked questions about your possible risk factors, symptoms, and any other health problems or concerns. 4 0 obj Be sure to tell your doctor if you have problems with bleeding or are taking medicines that could affect bleeding, such as aspirin or blood thinners. <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 594.96 842.04] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Guest editors for the symposium publication were Ivan Burger, Waltham Centre for Pet Nutrition, Leicestershire, UK and D'Ann Finley, University of California, Davis. The level of significance was set at p<0.05 with a 95% confidence interval. To reinforce this, tabby, which can be more commonly associated with crossbreed cats, had a much lower prevalence of hyperthyroidism. For example, a Abbreviations used: T3, triiodothyronine; T4, tetraiodothyronine; FT4, free tetraiodothyronine. How Hyperthyroidism Is Diagnosed - Verywell Health It can be concluded that there is no indication for preferential screening of cats according to gender or neutered status. However, once the underlying hyperthyroidism has been controlled, the heart changes will often improve or resolve simultaneously (Weichselbaum et al, 2003). Age, weight, gender, neutered status and colour were not significantly associated with hyperthyroidism or T4 result. Peterson M. E. Kintzer P. P. Cavanagh P. G. Fox P. R. Ferguson D. C. Johnson G. E. Becker D. V. Thoday, K. L., Seth, J. If cancer is found, other tests might be done to find out more about the cancer. Complete blood count (CBC). From all the DSH cats, 48 (31.6%) were hyperthyroid while 28 (56.0%) of all the other breeds were hyperthyroid. But ultrasound is usually the first choice for looking at the thyroid. If your doctor thinks a biopsy is needed, the simplest way to find out if a thyroid lump or nodule is cancerous is with a fine needle aspiration (FNA) of the thyroid nodule. WebHyperthyroidism means that too much hormone is being produced by your cats thyroid glands. Total T4 records of 202 clinically normal cats, tested for routine pre-anaesthetic bloods, using a Quantum Saturno 100 Vet wet chemistry analyser, were analysed retrospectively. Whether you or someone you love has cancer, knowing what to expect can help you cope. Results indicated a statistically significant association between breed and T4 result, with a much higher prevalence of hyperthyroidism and higher median T4 result in purebreed cats compared with crossbreed cats. Your doctor will examine you to get more information about possible signs of thyroid cancer and other health problems. These are the main hormones made by the thyroid gland. Copyright 2023 American Society for Nutrition. The majority of cats diagnosed with hyperthyroidism are middle to old aged (Figure 1) with a reported age range between 422 years (Gordon et al, 2003), yet only 5% of cats are younger than 10 years of age at time of diagnosis (Peterson, 2006). We couldnt do what we do without our volunteers and donors. A PET scan can be very useful if your thyroid cancer is one that doesnt take up radioactive iodine. <>>> According to the Feline Advisory Bureau (FAB) (2019) increased T4 levels in the majority of cases are due to a benign change. Incremental Improvements in Vitamin A Model-Based Compartmental Analysis in Anticipation of Real Data in Lactating Women, Food Environment and Supply on Dietary and Lifestyle Choices, Receive exclusive offers and updates from Oxford Academic. Philadelphia, Pa. Elsevier: 2014. However despite these differences, the normal ranges of the serum thyroid hormone concentrations, T3, T4 and FT4, of the two cat colony populations used in this study compared well with published data (Jones 1993, Peterson et al. Thyroid hormones affect most organs in the body and hyperthyroidism can occasionally cause secondary problems that may lead to further treatment being required (Graves, 2017). The prevalence of hyperthyroidism (elevated T4 levels) was 76 (37.6%) cats and the remaining 126 (62.4%) were euthyroid. 6 0 obj There was also increasing evidence that the presence of a goitre alone was a poor indicator of clinical hyperthyroidism (Boretti et al, 2009) and that suspected patients would therefore require a measurement of T4 and T3 biochemical blood test to confirm diagnosis (Peterson, 2006). To eliminate the effect of sex, regression analysis was carried out separately for male and female data to examine solely the influence of age on serum T4 values. According to Mooney and Peterson (2004) common signs of hyperthyroidism are usually quite subtle at first and can often go unrecognised, but can become severe as the disease progresses. The median weight of hyperthyroid cats was 4.3 kg with a range of 2.48.4 kg. Normal T4 ranges in cats vary from 12.87 nmol/Lto 38.61 nmol/L. The Total T4 Test This test is also known as the Baseline T4 Test and is the most commonly used test. A lobectomy can also be the main treatment for some early cancers, although for many cancers the rest of the thyroid will need to be removed as well (during an operation called a completion thyroidectomy). 1984). <> There were no published reports on the prevalence of a palpable goitre in cats and their relationship to T4 levels (Norsworthy et al, 2002). Third trimester: 0.48 4.71 uIU/mL. These changes are typically mild and should resolve with treatment of the hyperthyroid condition. The thyroid gland is located near the trachea (windpipe), just below the larynx (voice box). The association between neutered status and T4 result and hyperthyroidism was not statistically significant. Routine testing all cats for hyperthyroidism is not a common concept, it is under researched and difficult to measure. The serum T3 concentrations are presented in Figure 1(panel A) for all 52 cats. Because calcitonin can affect blood calcium levels, these may be checked as well. The American Cancer Society offers programs and services to help you during and after cancer treatment. (. Its also important to follow recommended screening guidelines, which can help detect certain cancers early. Does the Lens through Which We View Undernutrition Matter? Hyperthyroidism does not usually cause significant changes in the blood cell profile, with the exception of a mild increase in red blood cell numbers. Because hyperthyroidism in cats is due to the excess production of thyroid hormones (primarily T4), the blood T4 concentration is usually noticeably elevated in cats with the disease. Any result above or below the normal reference range was classified as being hypo/hyperthyroid. After surgery for thyroid cancer, whole-body radioiodine scans are useful to look for possible spread throughout the body. The T3 and T4 levels are usually normal in thyroid cancer. The impact of the current study could change the workings of small animal practices and the standard protocols put in place for routine blood testing to include T4 for cats. Statistical analysis indicated no effect of age or sex on the serum FT4 concentrations in cats. Histograms of all continuous variables were examined to determine whether or not they were normally distributed. The current study is designed to test whether it was worthwhile routinely testing those clinically normal cats in the high region of T4 levels for a definitive diagnosis of early hyperthyroidism. White cats had the highest median T4 result and tabby cats had the lowest result. Some cases, particularly those in the early stages of this condition, are trickier to diagnose with a single blood test. The range of T4 results for female cats was between 8153 nmol/litre, while males had a range of 14102 nmol/litre. Interestingly, data from this study showed sex to have a significant effect on serum T4 concentrations, in that female cats exhibited lower values compared with male cats, although data for both groups were within the normal range. Thyroid Tests and Results A downside of this is that it can cause the symptoms of hypothyroidism, including tiredness, depression, weight gain, sleepiness, constipation, muscle aches, and reduced concentration. In order to estimate the prevalence of elevated T4 levels in a sample of clinically normal cats, each case was determined as either having a low, normal or high T4 level depending on where it was in comparison to the normal reference range (1348 nmol/litre). Already have a myVCA account? Neutering may be an influencing factor. Treating Feline Hyperthyroidism - BluePearl Pet Hospital endobj Currently, most small animal practices are able to run inhouse blood tests with the option to add on a T4 test when required. Figure 1. Radioiodine scans work best if patients have high blood levels of thyroid-stimulating hormone (TSH, or thyrotropin). The median survival times reported are 25 (iodine 131 treatment),1 24 (radioiodine treatment),2 and 48 months (iodine 131 treatment),3 with a more recent paper citing 14 months (carbimazole or methimazole treatment alone or in combination with thyroidectomy).4 However, the differences in survival may be related to the cats' age at The American Cancer Society medical and editorial content team. Of the 170 crossbreed cats, 152 were DSH with a median T4 result of 44 nmol/litre compared with the remaining 50 cats that had a median T4 result of 51 nmol/litre, which was slightly higher. This might be done for different reasons: These tests can be done on tissue taken during a biopsy or surgery for thyroid cancer. WebProblem 1: Hyperthyroidism is suspected but the serum T4 concentration is normal Although serum total T 4 is preferable as a screening test for hyper - thyroidism, However, a small proportion of normal cats are known to have fT4 concentrations above the reference range. & Elton, R. A. Therefore, it is very important to document whether these changes are present at the outset, and then to follow these parameters as your cat is being treated for hyperthyroidism. This study demonstrated there was a statistically significant association between purity of breed and T4 result. In this situation, the PET scan may be able to tell whether the cancer has spread. Webcats. Therefore practices cannot suggest a recommended age at which to start testing for hyperthyroidism. If there is a reason to suspect you might have thyroid cancer, your doctor will use one or more tests to confirm the diagnosis. The condition can be diagnosed with a straightforward blood test taken by a vet. For people whose thyroid has been removed, TSH levels can be increased by stopping thyroid hormone pills for a few weeks before the test. WebTotal T4 Testing Guide: Feline Hyperthyroidism Dynamic range 0.520.0 g/dL(6.4257.4 nmol/L) Catalyst Total T4 results Subnormal <0.8 g/dL Normal 0.84.7 g/dL (<10.0 The most reliable test for confirming hyperthyroidism is a demonstration of an elevated basal T4 or free T4 concentration (generally considered to be >65 nmol/litre of T4 or free T4 >15 pmol/litre) (Quantum Veterinary Diagnostics, 2019). The concentration of fT4 is less affected by factors such as coexisting illness or medications. any breed other than DSH). However, the reference range extends The thyroid gland is located near the trachea (windpipe), just below the larynx (voice box). Medical treatment of hyperthyroidism is with drugs that inhibit synthesis of thyroid hormone in the thyroid gland such as methimazole/thiamazole. Therefore, it is important to evaluate your cat's blood sugar concentration to help rule out diabetes as a possible cause of these symptoms. Hyperthyroidism in Cats: Symptoms and Treatment | PetMD Search for other works by this author on: Reproductive manifestations of thyroid disease, Thyroid disease in the cat: diagnosis and treatment, Feline hyperthyroidism: pretreatment clinical and laboratory evaluation of 131 cases, Effect of nonthyroidial illness on serum thyroxine concentrations in cats: 494 cases, Mathematical Statistics and Data Analysis, Radioimmunoassay of serum total thyroxine and triiodothyronine in healthy cats: assay methodology and effects of age, sex, breed, heredity and environment, 1998 American Society for Nutritional Services, Impact Investing Holds Promise for Nutrition If Guided by Evidence. Overall, in order to confirm a diagnosis of hyperthyroidism, Panciera et al (2004) suggested the use of several other screening tests in conjunction with serum T4 levels, such as a complete blood count, biochemical analysis, urinalysis, radiography and cardiac ultrasonography. stream The majority of cases of hyperthyroidism can be diagnosed with a single blood test that measures the total thyroxine (T4) concentration. Hyperthyroidism in Cats - Cornell University College of Veterinary Glucagon-modified Liposomes Delivering Thyroid Hormone for Anti-obesity Therapy. A confirmation test for those results that came back as being hyperthyroid was then sent to the same external laboratory for a further diagnostic confirmation test. There was no significant association between hyperthyroidism and T4 result in either gender or neutered status in this study. By Cats with such a result do not have hyperthyroidism. The TSH level is usually normal in thyroid cancer. &(vlalD0#6fcHZ jd`hE,,[1-l@_}r DNjXNfsFY:,f35+%i-Fx[6sQ!E01pT iC*tg]+*"!.ni,"*ty2B[adp7-"G)fVu &%~R9NaKIw4{9JO5h`Su)*_#,SFYtu]~1r%Ab0) Available Every Minute of Every Day. People with MTC often have high blood levels of a protein called carcinoembryonic antigen (CEA). While carrying out the study, research and diagnosis was limited to one in-house T4 blood test result run on a Quantum Saturno 100 VET wet chemistry analyser with a normal range of T4 levels being between 1348 nmol/litre. This suggests that subclinical hyperthyroidism also exists in cats and might be diagnosed and treated before overt signs develop; 30% of cats suffering from hyperthyroidism do not present with clinical signs (Blaxter and Gruffydd-Jones, 1994), therefore routine testing could diagnose those cats that do not present with clinical signs as well as establishing evidence in veterinary medicine that early diagnosis improves the patient's outcome and that subclinical hyperthyroidism has a negative effect on the patient's health. 202 clinically normal cat results were obtained, of which, just over half (111; 55%) were female and 91 (45%) were male with 13 (6.4%) being entire and 189 (93.6%) being neutered. Diagnostic Testing for Feline Thyroid Disease: Hyperthyroidism An analysis of any associations between each factor was then conducted with the appropriate statistical test being carried out in SPSS. A summary of risk factors associated with T4 results and hyperthyroidism can be seen in Tables 4 and 5.