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). They were then filtered into being either hyperthyroid or euthyroid. FNA biopsies can also be used to get samples of swollen lymph nodes in the neck to see if they contain cancer. Medical treatment of hyperthyroidism is with drugs that inhibit synthesis of thyroid hormone in the thyroid gland such as methimazole/thiamazole. Histograms of all continuous variables were examined to determine whether or not they were normally distributed. This research has found that no studies have been conducted in regards to breed or gender that are particularly prone to developing hyperthyroidism. 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. 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. The median age of cats diagnosed with hyperthyroidism was 10.8 years with an overall sample range of 0.420.7 years. 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. 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. 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. 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. This is especially helpful for smaller nodules. If this happens, the doctor may order lab tests on the sample (see below). Does the Lens through Which We View Undernutrition Matter? A study conducted by Blois et al (2010) found that 1.85.5% of cats diagnosed with hyperthyroidism also had diabetes mellitus. Thyroid tumors can sometimes affect the vocal cords. Routine testing all cats for hyperthyroidism is not a common concept, it is under researched and difficult to measure. Statistical analysis indicated no effect of age or sex on the serum FT4 concentrations in cats. 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. 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. 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. You are not exposed to radiation during this test. Affiliate of Mars Inc. 2023 | Copyright VCA Canada Hospitals all rights reserved. As a reult the author recommends that practices should routinely test T4 levels in purebred cats. 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. In adults, normal total T4 levels are between 5.0 and 12.0g/dL (micrograms per deciliter). Any result above or below the normal reference range was classified as being hypo/hyperthyroid. 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. 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. 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. There was no significant association between hyperthyroidism and T4 result in either gender or neutered status in this study. (Solid nodules are more likely to be cancerous.) 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). The major change, found in approximately 75% of hyperthyroid cats, is related to mild increases in the liver related enzymes (alkaline phosphatase [AP], alanine aminotransferase [ALT], and aspartate aminotransferase [AST]). Quantum Veterinary Diagnostics (2019) sets the range of normal serum T4 levels between 1348 nmol/litre. 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. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide, This PDF is available to Subscribers Only. 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. <> WebThe thyroid gland is a 2-lobed gland in the neck. Looking at the results however, it was interesting to note that white, brown, blue and grey cats had the highest prevalence of hyperthyroidism, which can be more commonly associated with purebreed cats, which reinforced the results of the current study that there was a statistically significant association between hyperthyroidism and purebreed cats. endobj WebNormal ranges for thyroid function tests in infants and children T4: thyroxine; T3: triiodothyronine; TSH: thyroid-stimulating hormone; TBG: thyroxine-binding globulin. Each risk factor was then analysed individually by looking at numbers and percentages for categorical data and a level of deviation and mean/median for continuous variables. Imaging studies are usually done at a referral center. For this test, a small amount of radioactive iodine (called I-131) is swallowed (usually as a pill) or injected into a vein. If there proves to be a statistical significance to individual breeds then future studies should again conduct multivariable statistics and look at individual colours and their relationship to purebreed or crossbreed cats, and then compare the relationship to T4 results. This is why your healthcare provider will also check your free T4 and T3 levels. 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. 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). From a practice point of view, protocols should look at educating owners of the early signs of hyperthyroidism as well as encouraging frequent health check-ups and not by an age cut-off point as, from this research, there was no association between age and hyperthyroidism amongst clinically normal cats. Bleeding at the biopsy site is very rare except in people with bleeding disorders. Normal TSH levels for the average adult range from 0.4 4.0 mIU/L (milli-international units per liter) ( 3 ). The American Cancer Society is a qualified 501(c)(3) tax-exempt organization. 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. 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. Food was withheld from the cats for 16 h before sampling. Conclusion: Tests for CEA can help monitor this cancer. However Gordon et al (2003) documented a case report on juvenile hyperthyroidism in an 8-month-old kitten. 5th ed. stream The tests commonly used are the measurement of thyroxine, which is often abbreviated as T4, and a T3 suppression test. Over time, the iodine is absorbed by the thyroid gland (or thyroid cells anywhere in the body). A small amount of another thyroid hormone, triiodothyronine (T3), is also made by the thyroid gland. This was not statistically significant as the Mann-Whitney p-value=0.68. Davidge-Pitts CJ and Thompson GB. 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. 4 0 obj The association between neutered status and T4 result and hyperthyroidism was not statistically significant. All serum thyroid hormone concentrations of these cats were within the normal reference ranges as seen in Table 2 for this cat population. Hyperthyroidism in cats: should we be routinely testing for early diagnosis? The final nine categories of colour included (black, black and white, blue, brown, ginger, grey, tabby, tortoiseshell and white). These treatments should lead to a very low level of thyroglobulin in the blood within several weeks. The American Cancer Society medical and editorial content team. 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. Due to the evidence of non-clinical hyperthyroidism within cats, a key importance of this study was to determine whether there was any value in routinely blood testing those cats not presenting with clinical signs. endobj Results: It produces 2 iodine-containing hormones, T 3 and T 4, which affect many processes in the body. Increases in BUN and creatinine may be seen with kidney disease, or with dehydration or decreased blood flow to the kidneys. WebThere are two T4 tests, namely, the total T4 test and the free T4 test. This might be done for different reasons: These tests can be done on tissue taken during a biopsy or surgery for thyroid cancer. Urinalysis. DeVita, Hellman, and Rosenbergs Cancer: Principles and Practice of Oncology. Statistical Package for Social Sciences (SPSS) software assisted in the analysis of blood results and highlighted risk factors associated with the disease. However, further studies could look into this using a larger sample. Serum biochemistry profile. (. Its also important to follow recommended screening guidelines, which can help detect certain cancers early. However, in most cases, hyperthyroidism can be manageable if diagnosed early enough. The association between breed and hyperthyroidism was statistically significant as the Chi-Sqaure p-value=0.002. 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. Thyroid hormones have far-reaching effects on the body, in essence governing the body's metabolic rate. In a study conducted by Weichselbaum et al (2003), it was reported that of 149 cats with hyperthyroidism, 38% were receiving cardiac-related medication. Previous research indicated that hyperthyroidism was less likely to affect purebreed cats such as Siamese, however, the current study showed that in a sample of 202 clinically normal cats tested for hyperthyroidism, purebreed cats had a much higher prevalence of the disease. Copyright 2023 American Society for Nutrition. WebHyperthyroidism means that too much hormone is being produced by your cats thyroid glands. Changes in the initial screening tests may suggest the presence of hyperthyroidism, and may uncover other conditions, some of which may be related to increased thyroid hormone production while others may indicate other, non-related problems. The apparent age-related gradual decline of thyroid hormone levels in healthy cats should be considered when evaluating their thyroid status. 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. If left untreated and unmanaged these changes eventually compromise the normal heart function and can lead to heart failure. 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. 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. Samples were taken from each cat for serum thyroid hormone analysis at two intervals 9 wk apart. Values are means (n = 2). 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. The association between breed and T4 result was statistically significant as the Mann-Whitney p=0.002. Methods: 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. 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. From all the purebreed cats analysed, 20 (62.5%) had elevated T4 results compared to 56 (32.9%) which were crossbreeds. This type of treatment is described in Radioactive iodine (radioiodine) therapy. They can also be used to monitor certain cancers. This can mean blood tests for epinephrine (adrenaline) and a related hormone called norepinephrine, and/or urine tests for their breakdown products (called metanephrines). 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.
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