The most commonly used laboratory test to confirm a diagnosis is the determination of serum total T4 concentration. It can also be used to check the number and size of thyroid nodules as well ashelp determine if any nearby lymph nodes are enlarged because the thyroid cancer has spread. For example, if you are scheduled for surgery, tests will be done to check your blood cell counts, to look for bleeding disorders, and to check your liver and kidney function. Always check your labs reference range on your results report. A study conducted by Wakeling et al (2011) found that there was a higher prevalence of hyperthyroidism in euthyroid geriatric cats with undetectable TSH compared with those with detectable TSH concentrations. How long can a cat live with untreated hyperthyroidism? 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). Although hyperthyroidism is reported to be more common in older cats (Peterson, 2006) and rarely seen in cats less than 7 years of age, there was no significant correlation between T4 result and age in the current study of clinically normal cats. Figure 5. 7 0 obj Krista Williams, BSc, DVM; Kristiina Ruotsalo, DVM, DVSc, Dip ACVP; Margo S. Tant BSc, DVM, DVSc, Contributors: Krista Williams, BSc, DVM; Kristiina Ruotsalo, DVM, DVSc, Dip ACVP; Margo S. Tant BSc, DVM, DVSc. The prevalence of hyperthyroidism (elevated T4 levels) was 76 (37.6%) cats and the remaining 126 (62.4%) were euthyroid. Quantum Veterinary Diagnostics (2019) sets the range of normal serum T4 levels between 1348 nmol/litre. WebWhat is the thyroid gland? A summary of risk factors associated with T4 results and hyperthyroidism can be seen in Tables 4 and 5. Normal TSH levels for the average adult range from 0.4 4.0 mIU/L (milli-international units per liter) ( 3 ). endobj During the exam, the doctor will pay special attention to the size and firmness of your thyroid and any enlarged lymph nodes in your neck. The median T4 result of entire cats was 48 nmol/litre with a range between 31118 nmol/litre compared with neutered cats with a median T4 result of 45 nmol/litre and a range of 8153 nmol/litre. However, Gordon et al (2003) discussed several studies that have evaluated risk factors of hyperthyroidism which suggested that canned cat foods, the use of cat litter; the use of topical ectoparasitic preparations and living indoors were associated with the development of hyperthyroidism. 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). The normal range for free T4 is between 0.8 2.3 ng/dL. Peterson and Ward (2007) reported benign changes in 98% of cats with the remaining 2% having a thyroid carcinoma. For this reason, many doctors prefer MRI scans for differentiated thyroid cancer. These data confirm that the two cat populations used in this study, maintained on commercially prepared pet food, had a healthy thyroid status and are representative of the general pet population in terms of thyroid status. The majority 152 (75.2%) were DSH. Published data have indicated a significant similarity between the thyroid hormone levels of cats housed together, compared with values from individually housed cats, although it has been difficult to distinguish between environmental and genetic influences (Thoday et al. 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. People with MTC often have high blood levels of a protein called carcinoembryonic antigen (CEA). The apparent age-related gradual decline of thyroid hormone levels in healthy cats should be considered when evaluating their thyroid status. For this exam, the doctor looks down the throat at the larynx (voice box) with special mirrors or with a laryngoscope, a thin tube with a light and a lens on the end for viewing. In a study conducted by Weichselbaum et al (2003), it was reported that of 149 cats with hyperthyroidism, 38% were receiving cardiac-related medication. The vast majority of cases of hyperthyroidism are diagnosed by the combination of clinical history, initial laboratory screening tests, and the determination of T4 or fT4 blood concentrations. 'cKjk.h1Q&lDQUKjrX[;oeh{lShH?;x >y:x~>'h:8[##r~rzn}<6QcpR;*,.9| B%{#wT..mILT_X34BUM"+J[yf' However, thyroid hormones are vital in regulating important body functions including metabolism, body temperature, gastrointestinal function, heart rate and blood pressure. 1984). 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. The results from the two different cat populations were comparable. This study demonstrated there was a statistically significant association between purity of breed and T4 result. P < 0.005, r2 = 38%. Wednesday, October 2, 2019. Some cases, particularly those in the early stages of this condition, are trickier to diagnose with a single blood test. 1983). <> No, the thyroxine concentration may not always be increased. There was no significant association between hyperthyroidism and T4 result in either gender or neutered status in this study. Urinalysis. 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. There was also some evidence to suggest it was less common in Siamese cats (Mooney and Peterson, 2004). Results: There are several indicators which may suggest hyperthyroidism, but measuring the level of the thyroid hormone is the best test. The tests commonly used are the measurement of thyroxine, which is often abbreviated as T4, and a T3 suppression test. Normal T4 ranges in cats vary from 12.87 nmol/L to 38.61 nmol/L. Weve invested more than $5 billion in cancer research since 1946, all to find more and better treatments, uncover factors that may cause cancer, and improve cancer patients quality of life. For reprint requests, please see our Content Usage Policy. Medical treatment of hyperthyroidism is with drugs that inhibit synthesis of thyroid hormone in the thyroid gland such as methimazole/thiamazole. The serum T3 concentrations are presented in Figure 1(panel A) for all 52 cats. One way to raise TSH levels without withholding thyroid hormone is to give an injectable form of thyrotropin (Thyrogen) before the scan. Abbreviations used: T3, triiodothyronine; T4, tetraiodothyronine; FT4, free tetraiodothyronine. Your doctor will place a thin, hollow needle directly into the nodule to aspirate (take out) some cells and a few drops of fluid into a syringe. MRI scans are also very helpful in looking at the brain and spinal cord. Radioiodine scans can be used to help determine if someone with a lump in the neck might have thyroid cancer. endobj The administration of drugs for other medical conditions may affect the concentration of thyroxine. Copyright 2023 Most adults older than 30 years with elevated TSH but normal FT 4 levels do not benefit from thyroid hormone therapy, and 60% normalize within five years. Whether you or someone you love has cancer, knowing what to expect can help you cope. The association between gender and T4 result and hyperthyroidism was not statistically significant. Much of the variation in published reference ranges for feline thyroid hormone levels is due to different techniques, assays or cat populations. However this was again not statistically significant with the Chi-Square p-value=0.56 and can be explained by the few cases recorded as being entire. 1983). This means that they are larger than about 1 centimeter (about 1/2 inch) across. endobj Symptoms can include an increase in appetite, weight loss and a poor coat. The normal range for the TSH test is approximately 0.5 to 5.0 milli-international units per liter (mIU/L). Many hyperthyroid cats have increases in the kidney related parameters (blood urea nitrogen [BUN] and creatinine). 202 clinical records from the practice were tabulated into a Microsoft excel spreadsheet for analysis where information was gathered regarding gender, age, breed, colour, weight, T4 result and T4 description (hyperthyroid/euthyroid) of each patient case. It could be argued that there is no need to treat the condition if there are no clinical signs of the disease. However, many organizations agree that a reading of 2.5 or less is truly ideal for normal thyroid levels, with anything 2.5 4.0 mIU/L considered at risk. DSH had a range of T4 results between 8153 nmol/litre and the remaining cats had a range between 25103 nmol/litre. To ensure that all of the cats were of equivalent health status, every cat was given a full veterinary examination and samples were taken for routine blood biochemistry and hematology, feline immumodeficiency virus and feline leukemia virus. gender, neutered status, age, breed, colour and weight. If the body is producing too much thyroid hormone and is left untreated then there can be serious damage to vital organs like the heart and kidneys. If cancer is found, other tests might be done to find out more about the cancer. (. The aim was to diagnose subclinical patients with T4 levels that were beginning to rise and to potentially alleviate changes to the cardiac muscle by treating those cases diagnosed before the onset of clinical signs presented. Pheochromocytomas can cause problems during surgery if the patient is under anesthesia (in a deep sleep). Philadelphia, Pa. Elsevier: 2014. Thyroxine levels in the blood naturally fluctuate throughout the day, depending on the metabolic needs of the cat. To date, there have been no studies conducted in regards to breed that may be prone to hyperthyroidism, however Mooney and Peterson (2004) reported it being less common in Siamese cats. The significant negative correlation between serum tetraidodothyronine (T4) concentration and age in female cats (n = 38) using simple regression; P < 0.001, r2 = 33%. Webcats <5 kg 20 micrograms of Tertroxin cats >5 kg 30 micrograms of Tertroxin Collect second blood sample 2 6 hours after final dose Label both samples clearly and request TT4 and A variety of tests were performed which included a non-parametric Mann-Whitney test for an association between a continuous variable and a binary categorical variable; a Chi-square test for an association between two categorical variables; a non-parametric Spearman test for an association between two continuous variables, as well as a non-parametric Kruskal-Wallis test for an association between a continuous variable and a categorical variable with more than two categories. Records from cats tested for routine pre anaesthetic bloods (including T4) over a year's period that did not show signs of hyperthyroidism were extracted and retrospectively analysed. Here you'll find in-depth information on specific cancer types including risk factors, early detection, diagnosis, and treatment options. Similarly to breed, colour was another risk factor that was grouped into measurable categories due to the wide range documented. 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. (Solid nodules are more likely to be cancerous.) Future studies should look at conducting multivariable statistics, looking at age in purebreed cats diagnosed as being hyperthyroid to find any association along with other risk factors within the purebreed category. 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. Data were compared by ANOVA to determine any differences between age and sex for all thyroid parameters. There was therefore no correlation between weight and T4 result with the Spearman's Non-Parametric p-value=0.86 as shown in Figure 5. 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. The biopsy samples are then sent to a lab, where they are looked at to see if the cells look cancerous or benign. The median age of cats diagnosed with hyperthyroidism was 10.8 years with an overall sample range of 0.420.7 years. The function of the thyroid gland is controlled by the pituitary gland at the base of the brain, through a hormone called thyroid stimulating hormone (TSH). 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. <>>> endobj In some To reinforce this, 45 (40.5%) of all the female cats were hyperthyroid while 31 (34.1%) of all the male cats were hyperthyroid, which showed hyperthyroidism was more prevalent in female cats, but again this was not statistically significant with the Chi-Square p=0.38. Since hypothyroidism (decreased thyroid function due to disease of the thyroid glands), is very rare in cats, such a decrease is usually due the presence of an illness other than thyroid disease. Statistical Package for Social Sciences (SPSS) software assisted in the analysis of blood results and highlighted risk factors associated with the disease. Nicola D. Skinner, Thyroid Hormone Levels in Cats: Colony Average and the Decrease with Age, The Journal of Nutrition, Volume 128, Issue 12, December 1998, Pages 2636S2638S, https://doi.org/10.1093/jn/128.12.2636S. Background: 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, in turn, allows more tests to be performed easily producing immediate results with a huge increase in offering clients the option of pre-anaesthetic blood tests. 5 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). The doctor usually repeats this 2 or 3 more times, taking samples from several areas of the nodule. Therefore, the presence of significant alterations in any of these blood parameters may alert your veterinarian to the existence of other disease conditions. These help vets measure the amount of thyroxine in the cats body. Diagnosing Hyperthyroidism in Cats (T3 & T4 Tests) - Cat-World 3 0 obj Hot nodules usually are not cancerous, but cold nodules can be benign or cancerous. This research cannot recommend an age to routinely test for hyperthyroidism due to the results not being statistically significant with Spearman's Non-Parametric p-value=0.08. A group of 117 cats (50 neutered males, 67 entire females), ranging in age from 6 mo to 10 y, were sampled from the Waltham Centre for Pet Nutrition, UK. T3 and T4 (thyroid hormones) These are the main hormones made by the thyroid gland. This test can help determine if a thyroid nodule is solid or filled with fluid. Serum T4 concentrations for female cats also showed an age-related decline. 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. Consequently, testing for hyperthyroidism has become easier and this paper recommends it to be considered as part of the routine blood tests that are run on a daily basis within the practice. 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. The normal range of TSH levels in adults is between 0.4 to 4.0 mIU/L (milli-international units per liter). Regression analysis showed a significant negative correlation between age and T3 levels in the age range 1.25 to 5.7 y (P < 0.005, r2 = 38%), with a mean value of 0.53 0.15 nmol/L (Fig. 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.