Therefore, the presence of significant alterations in any of these blood parameters may alert your veterinarian to the existence of other disease conditions. Hyperthyroidism is a multisystemic disorder and is a very common endocrinopathy affecting older cats, typically older than 8 years of age (Ward, 2007; Peterson, 2012). 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. Radioactive iodine can also be used to treat differentiated thyroid cancer, but it is given in much higher doses. Thyroxine levels in the blood naturally fluctuate throughout the day, depending on the metabolic needs of the cat. The white blood cells, red blood cells, and platelets (cellular components involved in the clotting process) are evaluated in this test. T3 and T4 (thyroid hormones) These are the main hormones made by the thyroid gland. 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. WebThe thyroid gland is a 2-lobed gland in the neck. 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. Serum T4 concentrations for female cats also showed an age-related decline. This means that they are larger than about 1 centimeter (about 1/2 inch) across. <>>>
Imaging tests may be done for a number of reasons: People who have or may have thyroid cancer will get one or more of these tests. Even when a nodule is large enough to feel, most doctors prefer to use ultrasound to guide the needle. This research also provided an understanding that, within the small sample of cats tested, routine testing of all cats for hyperthyroidism did indeed cause an overall improvement in diagnosing the disease as it diagnosed 37.6% of cats as being hyperthyroid without showing any signs of the disease, which would not have been recognised until a much later date, if at all. 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. However there was no statistically significant relationship between either hyperthyroidism or T4 result and coat colour. However Gordon et al (2003) documented a case report on juvenile hyperthyroidism in an 8-month-old kitten. FAB (2019) described the effect of elevated thyroid hormones on the heart which caused an increased heart rate and a stronger contraction of the heart muscle. &(vlalD0#6fcHZ jd`hE,,[1-l@_}r
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&%~R9NaKIw4{9JO5h`Su)*_#,SFYtu]~1r%Ab0) Normal T3 levels indicate that someones thyroid is producing an adequate amount of T3 hormone. A significant age-related decline for T3 values was observed up to 56 y of age, followed by a plateau, with no correlation between age and T3 values in older cats (>6 y). Normal TSH levels for the average adult range from 0.4 4.0 mIU/L (milli-international units per liter) ( 3 ). Neutering may be an influencing factor. This leads to low thyroid hormone levels (hypothyroidism) and causes the pituitary gland to release more TSH, which in turn stimulates any thyroid cancer cells to take up the radioactive iodine. WebT3 levels are usually elevated or high-normal in hyperthyroid cats. This research has found that no studies have been conducted in regards to breed or gender that are particularly prone to developing hyperthyroidism. 1. Therefore, the effects of increased thyroid hormone concentrations may be seen in many initial blood and serum screening tests. Hyperthyroidism in cats: should we be routinely testing for early diagnosis? <>/ExtGState<>/XObject<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 594.96 842.04] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>>
Levels of these hormones may also be measured to get a sense of thyroid gland function. 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. WebHyperthyroidism means that too much hormone is being produced by your cats thyroid glands. The majority of cases of hyperthyroidism can be diagnosed with a single blood test that measures the total thyroxine (T4) concentration. 6 0 obj
Philadelphia, Pa. Elsevier: 2014. On rare occasions, additional tests such as the T3 suppression test or advanced imaging studies of the thyroid gland (thyroid scintigraphy) may need to be performed. The association between neutered status and T4 result and hyperthyroidism was not statistically significant. Free T4 by equilibrium dialysis Free T4 (FT4) is the non-protein bound thyroxine present in the blood. It is important to acknowledge that cats with hyperthyroidism can have normal T4 levels despite having the disease thus care had to be taken when interpreting laboratory results (Graves, 2011). Hypothyroidism (a decreased production of thyroid hormones) is very uncommon in cats and is usually related to previous therapy for a hyperthyroid condition, or due to a congenital condition (originating from birth). Data were compared by ANOVA to determine any differences between age and sex for all thyroid parameters. 8 0 obj
The prevalence of hyperthyroidism (elevated T4 levels) was 76 (37.6%) cats and the remaining 126 (62.4%) were euthyroid. Anything above the top end of the normal range confirms the diagnosis. If hyperthyroidism is suspected on clinical grounds but cannot be confirmed by repeated basal T4 estimations, a T3 suppression test can be performed. Most FNA biopsies will show that the thyroid nodule is benign. The significant negative correlation between serum tetraidodothyronine (T4) concentration and age in female cats (n = 38) using simple regression; P < 0.001, r2 = 33%. Levels of TSH, which is made by the pituitary gland, may be high if the thyroid is not making enough hormones. 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. The biopsy samples are then sent to a lab, where they are looked at to see if the cells look cancerous or benign. Peterson et al (1987) did not identify sex or breed predispositions of hyperthyroidism although their findings showed a relatively low prevalence in pedigree cats. 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. WebIn patients whose signs are consistent with hyperthyroidism but whose thyroid levels are towards the mid-to-high end of the normal range, further blood testing and imaging y3'N{*m!VDQ;HH[nWA"[DhQ[rw4!/CVXP{.j|pHZxt^tJ?RwMo?zl} Z
You can help reduce your risk of cancer by making healthy choices like eating right, staying active and not smoking. It is mainly during the rapid growth phase (rapidly growing puppies up to 14-16 g/dL) and can be determined again as the growth phase In bilateral cases, both thyroid glands are affected, although one may be more affected than the other (Peterson, 2012). <>
A number of factors known to influence the serum concentrations of thyroid hormones have been well documented, e.g., nonthyroidal illness (Peterson et al. The two values for each cat were combined and the mean value obtained for comparative purposes. From all the DSH cats, 48 (31.6%) were hyperthyroid while 28 (56.0%) of all the other breeds were hyperthyroid. endobj
To achieve a balanced trial design, 52 cats with ages evenly distributed between 1.25 and 14 y (mean age 6.78 3.62 y) were used for the study. The association between breed and hyperthyroidism was statistically significant as the Chi-Sqaure p-value=0.002. From the 202 clinically normal cats reviewed in this study, 76 were found to have elevated T4 levels without recognition from the owners, or without showing common clinical signs of the disease. WebNormal ranges for thyroid function tests in infants and children T4: thyroxine; T3: triiodothyronine; TSH: thyroid-stimulating hormone; TBG: thyroxine-binding globulin. One way to raise TSH levels without withholding thyroid hormone is to give an injectable form of thyrotropin (Thyrogen) before the scan. Urinalysis. Weight plotted against T4 result. Complete blood count (CBC). The mean T3 value was 0.46 0.08 nmol/L; within In: DeVita VT, Lawrence TS, Rosenberg SA, eds. As such, the current study built on previous studies of diagnosed hyperthyroidism and estimated the prevalence of the disease and identified risk factors associated with hyperthyroidism within subclinical cats. 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. 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. They were then filtered into being either hyperthyroid or euthyroid. As 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. Purebreed cats are a group that could be routinely tested for hyperthyroidism, as results showed a statistically significant association between breed and T4 result. According to Capen and Martin (2003) this is the result of a larger number of cats receiving veterinary medical care, an improvement in assays for thyroid hormones, detailed characteristics of hyperthyroidism and increased awareness of its occurrence in cats by veterinary surgeons (VS). 9 0 obj
Cancer is clearly diagnosed in only about 1 of every 20 FNA biopsies. Much of the variation in published reference ranges for feline thyroid hormone levels is due to different techniques, assays or cat populations. If your cat has a mild or early case of hyperthyroidism, the thyroxine concentration may occasionally dip into the normal range. There was also some evidence to suggest it was less common in Siamese cats (Mooney and Peterson, 2004). Diagnosis and treatment could therefore be valuable even in subclinical cats. A greater variety of tests may be required to confirm and get a definitive diagnosis as cats may be tested before a serum total T4 concentration exceeds the reference range, as well as there being an increasing number of cats with clinical signs of hyperthyroidism and palpably large thyroid glands whose baseline serum total thyroid hormone concentrations are within the normal or borderline range, making diagnosis difficult. The American Cancer Society is a qualified 501(c)(3) tax-exempt organization.
All serum thyroid hormone concentrations of these cats were within the normal reference ranges as seen in Table 2 for this cat population. The thyroid gland is located near the trachea (windpipe), just below the larynx (voice box). Clients are becoming more willing to diagnose and have routine blood tests carried out on their pets as well as to continually assess their pet's performance, thus making routine testing possible. In most cases, diagnosing hyperthyroidism is straightforward: high levels of thyroid hormone in the bloodstream (total T4 or TT4) along with the typical signs. Elderly human patients with subclinical hyperthyroidism have been shown to develop obvious hyperthyroidism at a rate of 29% per year, and if left untreated can have effects on the cardiovascular function with an increased risk of developing atrial fibrillation as well as affecting bone density (Wakeling et al, 2011). Measuring For this test, a small amount of radioactive iodine (called I-131) is swallowed (usually as a pill) or injected into a vein. Screening T4 tests should be performed routinely in cats over seven yrs of age to facilitate early diagnosis. The majority of cases occur in cats over thirteen 2. If your veterinarian thinks your cat is at risk, he will advocate for tests to evaluate your cat completely. The same external laboratory was used each time. Symptoms can include an increase in appetite, weight loss and a poor coat. Unlike human diagnosis, there is usually no advantage in determining T3 concentration (which occasionally remains within a normal range) or performing a thyroid stimulating hormone (TSH) or thyrotrophin releasing hormone (TRH) stimulation test according to Broome et al (1988). In light of this, there has been a direct improvement in the efficacy of the diagnostic tests used to confirm hyperthyroidism with the opportunity to routinely test those cats with early or mild signs of the disease. All cats had been maintained on a variety of nutritionally complete commercial cat foods. 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. However, thyroid hormones are vital in regulating important body functions including metabolism, body temperature, gastrointestinal function, heart rate and blood pressure. Thyroglobulin is a protein made by the thyroid gland. Future studies should look at conducting multivariable statistics, specifically looking at age in purebreed cats diagnosed as being hyperthyroid in order to find any association along with other risk factors within the purebreed category. The serum concentrations of triiodothyronine (T3),2 tetraiodothyronine (T4) and free tetraiodothyronine (FT4) were determined by SCL Bioscience Services Ltd., Cambridge, UK and the Central Diagnostic Laboratory, Victoria, Australia, using the following commercial radioimmunoassay kits: T3, Amersham/Kodak (Buckinghamshire, UK) IM 3001/3004; T4, DPC (Wales, UK) double antibody method KT 4D1/4D5; FT4, Amersham/Kodak monoclonal method, IM 5051/5054 validated for cat serum. Also in adults, the normal range for T3 levels is between 80 and 220 ng/dL In a study conducted by Weichselbaum et al (2003), it was reported that of 149 cats with hyperthyroidism, 38% were receiving cardiac-related medication. 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. To describe serum total thyroxine (T4) concentration levels in a population of clinically normal cats; to determine the range of T4 levels in clinically normal cats; to estimate the prevalence of hyperthyroidism in clinically normal cats and to identify risk factors for elevated T4 levels in clinically normal cats tested for hyperthyroidism and are diagnosed. Any result above or below the normal reference range was classified as being hypo/hyperthyroid. <>
To establish the thyroid hormone levels in colony cats, blood samples were taken from the cephalic vein from two different colony populations of domestic short-haired cats. Serum SDMA reference levels in puppies have been determined slightly higher than the adult. No correlation was found, however, between age and T3 serum concentrations in older cats, in the range of 6 to 13.6 y. The median age was 11.4 years with a range between 0.422.6 years, and the median weight of the cats analysed was 4.4 kg with a range between 1.98.4 kg. T4 levels greater than 48 nmol/litre indicated inadequate treatment or untreated hyperthyroidism, T4 levels ranging between 3545 nmol/litre required clinical assessments, while T4 levels less than 13 nmol/litre indicated hypothyroidism or over dosing of medication (Quantum Vet Diagnostics, 2019). 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. & Elton, R. A. Abnormal areas of the thyroid that have less radioactivity than the surrounding tissue are called cold nodules, and areas that take up more radiation are called hot nodules. Figure 2. Schneider DF, Mazeh H, Lubner SJ, Jaume JC, and Chen H. Chapter 71: Cancer of the Endocrine System. Whether you or someone you love has cancer, knowing what to expect can help you cope. The median age of euthyroid cats was 11.7 years with a range between 0.422.6 years. on February 20, 2019. 5th ed. Although diagnosis in most cats is relatively straightforward, studies have shown that several cats suspected of having hyperthyroidism do not present with clinical signs or a palpable goitre. <>
Over time, with untreated hyperthyroidism, the muscle of the left ventricle of the heart enlarges and thickens (left ventricular hypertrophy). A small amount of another thyroid hormone, triiodothyronine (T3), is also made by the thyroid gland. Thyroid hormones have far-reaching effects on the body, in essence governing the body's metabolic rate. 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. Radioiodine scans work best if patients have high blood levels of thyroid-stimulating hormone (TSH, or thyrotropin). The association between age and T4 result and hyperthyroidism was not statistically significant. Gillian M Gordon
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. The doctor usually repeats this 2 or 3 more times, taking samples from several areas of the nodule. The normal range for the TSH test is approximately 0.5 to 5.0 milli-international units per liter (mIU/L). These changes are typically mild and should resolve with treatment of the hyperthyroid condition. SDMA reference range in kittens and adult cats is almost similar. Serum thyroid hormone concentrations in two cat populations1,2. 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. A CT scan can also be used to look for spread into distant organs such as the lungs. Previously, there have been no reports in the literature of hyperthyroidism in cats less than 4 years old. Again this reinforced the fact that age was not statistically associated with hyperthyroidism in clinically normal cats and there was no correlation between age and T4 result as shown in Figure 4 with the Spearman's Non-Parametric p value=0.08. 3 0 obj
However, there are many interactions between reproductive function and thyroid function that may affect normal thyroid hormone levels (Johnson 1994), the mechanisms of which are not yet fully understood. WebThe TSH level is usually normal in thyroid cancer. Hyperthyroidism was considered very unlikely due to the patient's age, however, T4 levels were evaluated at a laboratory on three occasions as a comprehensive feline blood panel, in which a definitive diagnosis of hyperthyroidism was made. Thyroid cancer may be diagnosed after a person goes to a doctor because of symptoms, or it might be found during a routine physical exam or other tests. The Mann-Whitney p value= 0.33. No such effect was observed for serum T3 or FT4 concentrations. Glucagon-modified Liposomes Delivering Thyroid Hormone for Anti-obesity Therapy. There are several indicators which may suggest hyperthyroidism, but measuring the level of the thyroid hormone is the best test. White cats also had the highest percentage prevalence of hyperthyroidism of 75%, brown being 57.1% and blue 50%, which can commonly be associated with purebreed colours; thus purebreeds showed a higher prevalence of hyperthyroidism. Accessed at https://www.nccn.org/professionals/physician_gls/pdf/thyroid.pdf on May 12, 2020. 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. Due to the large range of breeds recorded (Abyssinian, Bengal, Birman, Bombay, British Shorthair (BSH), Burmese, Domestic Longhair (DLH), Domestic Shorthair (DSH), Exotic Shorthair, Main Coon, Persian, Ragdoll, Russian and Siamese) they were grouped into statistically significant groups that included crossbreed v purebreed and DSH v other. Physician Data Query (PDQ). 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. But they can help show if your thyroid is working normally, which may help the doctor decide what other tests may be needed. 1, panel B). Peterson (2012) suggested that adenomas are bilateral in more than 70% of cases and unilateral in fewer than 30%. It is very common in older cats and most cases can be treated successfully. This type of biopsy can sometimes be done in your doctors office or clinic. Ultrasound uses sound waves to create images of parts of your body. Gordon et al (2003) described certain risk factors related to hyperthyroidism that included living indoors, canned cat foods, topical ectoparasitic preparations and the use of litter trays. But ultrasound is usually the first choice for looking at the thyroid. Published data are conflicting regarding the effects of age on the thyroid hormone levels in euthyroid cats. The arbitrary age ranges established (Table 1) to achieve a balanced trial design were not used in statistical analysis. <>
The median T4 result for crossbreeds was 43.5 nmol/litre against that of purebreeds which was higher at 55 nmol/litre. Similarly, it is impossible to accurately predict if these parameters will increase or decrease with treatment of hyperthyroidism. 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. This test is also used to look for the possible recurrence of MTC after treatment. If this happens, the doctor may order lab tests on the sample (see below). 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. Copyright 2023 American Society for Nutrition. 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. Reference TSH ranges remain controversial, but for most people, the normal Hyperthyroidism, a multisystemic disorder resulting from the excessive production and secretion of thyroid hormones, is considered to be the most common endocrine disease of middle-aged and old cats, with cats over the age of 6 y at risk. Figure 5. Although there was a slight difference between the results, there was no statistically significant difference as the Mann-Whitney p-value=0.42. xWnF}G2VD:"puhY-%2)u+Siw6v'+\'o_oi2I6[nI>Ln
q2f5 This is why your healthcare provider will also check your free T4 and T3 levels. For female data, Figure 2, a significant negative correlation between age and T4 values was determined (P < 0.001, r2 = 33%). Diagnosing Hyperthyroidism in Cats (T3 & T4 Tests) - Cat-World We couldnt do what we do without our volunteers and donors. Less than 2% of the hyperthyroid conditions in cats are due to malignant (cancerous) tumors of the thyroid glands. American Cancer Society medical information is copyrightedmaterial. 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. any breed other than DSH). Accessed at https://www.cancer.gov/types/thyroid/hp/thyroid-treatment-pdq#_313_toc. According to the Feline Advisory Bureau (FAB) (2019) increased T4 levels in the majority of cases are due to a benign change. 7 0 obj
1984). The research was conducted in a small-animal practice in Glasgow that routinely tested all cats for hyperthyroidism. It does not appear, therefore, that cats housed in similar environments (such as colony cats) require specific reference ranges. Long-term percutaneous triclosan exposure induces thyroid damage in mice: Interpretation of toxicity mechanism from metabolic and proteomic perspectives. Peterson and Ward (2007) reported benign changes in 98% of cats with the remaining 2% having a thyroid carcinoma. 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. Bleeding at the biopsy site is very rare except in people with bleeding disorders. The mean serum T3, T4 and FT4 hormone concentrations ( sd), determined for the two colony populations of cats at the Waltham Centre and Wodonga, Australia to establish a normal reference range for each colony, are presented in Table 2. T4 is the most commonly measured hormone that is produced directly by the thyroid gland, and is subsequently released to circulate throughout the body. The most commonly used laboratory test to confirm a diagnosis is the determination of serum total T4 concentration. Because medullary thyroid cancer cells do not absorb iodine, radioiodine scans are not used for this cancer. 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). The median weight of hyperthyroid cats was 4.3 kg with a range of 2.48.4 kg. 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. Determination of fT4 involves a single blood sample that is sent to a referral laboratory for a special test called free T4 by equilibrium dialysis (fT4EqD). Histograms of all continuous variables were examined to determine whether or not they were normally distributed. NCCN Clinical Practice Guidelines in Oncology: Thyroid Carcinoma. This type of treatment is described in Radioactive iodine (radioiodine) therapy. 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. 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, Oxford University Press is a department of the University of Oxford. By
Similarly, the most common crossbreed cat (DSH) was found to have a much lower prevalence of hyperthyroidism than cats categorised as other (i.e. 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. Free thyroxine concentration (fT4) is the portion of the thyroxine hormone that is not bound to any blood proteins. WebSome cats may show no visible hyperthyroidism symptoms, which can make it difficult to diagnose in the first instance. In contrast, this study demonstrated a much higher prevalence of hyperthyroidism and higher median T4 result in purebreed cats compared with crossbreed cats. The T3 and T4 levels are usually normal in thyroid cancer. The median T4 result was 45 nmol/litre with a range between 8153 nmol/litre as seen in Figure 3. Surgical biopsies and lobectomies are done in an operating room while you are under general anesthesia (in a deep sleep). Background:
Before the biopsy, local anesthesia (numbing medicine) may be injected into the skin over the nodule, but in most cases an anesthetic is not needed. Unfortunately, there are no known preventive measures cat owners can take to avoid hyperthyroidism. Fecal Metabolome: New Addition to the Toolbox for Dietary Assessment? The association between weight and T4 result and hyperthyroidism was not statistically significant. The majority 152 (75.2%) were DSH.