Epidemiology of thyroid diseases

Size: px

Start display at page:

Download "Epidemiology of thyroid diseases"

Aron Lee
5 years ago
Views:

1 Faculty of Medicine Epidemiology of thyroid diseases By Hatim Jaber MD MPH JBCM PhD

2 Presentation outline Time Introduction : Epidemiology and Overview of Thyroid Dysfunction 11:00 11:10 Risk factors of Thyroid Dysfunction 11:10 11:20 Iodine and thyroid 11:20 11:30 Phenylketonuria 11:30 11:50 2

3 79 million newborns protected from losses in learning ability in the developing world Less than 50% (38) 50%-89% (37) 90% or more (20) No data (82) No recent data (19) Source: SOWC

4 Overview of Thyroid Dysfunction Hypothyroidism Hyperthyroidism Disorders of the thyroid are common and consist of 2 general presentations: changes in the size or shape of the gland or changes in secretion of hormones from the gland. Hypothyroidism refers to the inadequate production of thyroid hormone or diminished stimulation of the thyroid by TSH; hyperthyroidism refers to those conditions in which thyroid hormones are excessively released due to gland hyperfunction. 4

5 Epidemiology of Thyroid Dysfunction Hypothyroidism and Hyperthyroidism Thyroid disorders are amongst the most prevalent of medical conditions Their manifestations vary considerably from area to area and are determined principally by the availability of iodine in the diet. Almost one-third of the world's population lives in areas of iodine deficiency In areas where the daily iodine intake is below 50 μg, goitre is usually endemic, and when the daily intake falls below 25 μg, hypothyroidism is seen The prevalence of goitre in areas of severe iodine deficiency can be as high as 80 %. 5

6 Epidemiology of Thyroid Dysfunction Hypothyroidism and Hyperthyroidism The most common cause of thyroid disorders worldwide is iodine deficiency, leading to goitre formation and hypothyroidism. In iodine-replete areas, most persons with thyroid disorders have autoimmune disease. The prevalence of thyroid dysfunction increases with age and diagnosis may be complicated in the older age group due to concomitant disease or therapy 6

7 Epidemiology of Thyroid Dysfunction Hypothyroidism and Hyperthyroidism Thyroid Disorder and Diseases (Graves and Hashimotos) are growing worldwide. 200 million worldwide have a Thyroid Disorder 80% of all cases of Graves Disease are diagnosed in females 20% of Thyroid Storm cases end in death 80% of all Thyroid Disease cases are diagnosed as Hypothyroidism and 20% Hyperthyroidism Females are 5 times more likely to develop a hypothyroid disease condition over males 20% of people with Diabetes will experience an onset of a thyroid disorder 50% of children with parents having a thyroid disorder may develop a thyroid disorder themselves by age 40 7

Participants With Elevated TSH, % Prevalence of Elevated Serum TSH by Decade of Age and Gender 18 16 14 12 10 8 6 4 2 0 13-19 NHANES III Study (N=17 353) 20-29 Males Females 30-39 40-49 50-59 60-69

8 Participants With Elevated TSH, % Prevalence of Elevated Serum TSH by Decade of Age and Gender NHANES III Study (N=17 353) Males Females >80 At <40 years of age, prevalence is relatively low and similar between males and females At 40 years of age, a higher percentage of female patients have elevated TSH levels Age, y Hollowell JG, et al. J Clin Endocrinol Metab. 2002;87:

9 Disorders Hypothyrodism Hyperthyroidism Congenital Acquired 9

10 Typical Thyroid Hormone Levels in Thyroid Disease TSH T 4 T 3 Hypothyroidism High Low Low Hyperthyroidism Low High High Measurement of the total plasma hormone concentration may not provide an accurate assessment of thyroid gland activity because total hormone concentration is affected by changes in either the amount of thyroxine-binding globulin (TBG) or the affinity of hormones to TBG in plasma. 10

11 Hypothyroidism Hypothyroidism is a disorder with multiple causes in which the thyroid fails to secrete an adequate amount of thyroid hormone The most common thyroid disorder Usually caused by primary thyroid gland failure Also may result from diminished stimulation of the thyroid gland by TSH known as myxedema when severe 11

12 Causes of hypothyroidism Congenital Autoimmune (Hashimoto) Iodine deficiency Subacute thyroiditis Drugs (amiodarone) Irradiation Thyroid surgery Central hypothyroidism (radiotherapy, surgery, tumor) 12

13 Clinical features of Acquired hypothyroidism Weight gain Goitre Short sature Fatigue Constipation Dry skin Cold Intolerance Hoarseness Sinus Bradycardia 13

14 Hashimoto s Disease Most common cause of hypothyroidism Autoimmune lymphocytic thyroiditis Antithyroid antibodies: Thyroglobulin Ab Microsomal Ab TSH-R Ab (block) Females > Males Runs in Families! 14

15 Subacute (de Quervain s) Thyroiditis Preceding viral infection Infiltration of the gland with granulomas Painful goitre Hyperthyroid phase Hypothyroid phase 15

Congenital Hypothyroidism- CH Clinical condition associated with decreased function of the thyroid gland and a decrease in the circulating level of thyroid hormones 1:3500 to 1:4000 newborns One

16 Congenital Hypothyroidism- CH Clinical condition associated with decreased function of the thyroid gland and a decrease in the circulating level of thyroid hormones 1:3500 to 1:4000 newborns One of most common preventable causes of mental retardation Female : Male is 2 : 1 Almost all affected ---have no S/S at birth Biochemical (screening) The most treatable cause of mental retardation 16

17 Causes of Congenital Hypothyroidism 1. Dysgenesis (85%) 2. Ectopic 3. Enzyme defect (10%) 4. Pituitary, Hypothalamic 5. Iodine deficiency The most common cause of congenital hypothyroidism is iodine deficiency. 17

18 Congenital Hypothyroidism suspect X Clinical Biochemical (screening) Optional Confirm Lab ( TSH & FT4 ) T scan B age Rx & FU Thyroxine Growth & D TSH & FT4 18

Populations at Risk for Hypothyroidism Women Prior history of Graves disease or postpartum thyroid dysfunction Elderly Other autoimmune disease Family history of Thyroid disease Pernicious

19 Populations at Risk for Hypothyroidism Women Prior history of Graves disease or postpartum thyroid dysfunction Elderly Other autoimmune disease Family history of Thyroid disease Pernicious anemia Type 1 Diabetes mellitus Caraccio N, et al. J Clin Endocrinol Metab. 2002;87: Carmel R, et al. Arch Intern Med. 1982;142: Perros P, et al. Diabetes Med. 1995;12:

20 Hypothyroidism Causes Primary: chronic autoimmune thyroiditis, prior radiation therapy (either 131I or radiation to head and neck); subtotal / total thyroidectomy; defective TH production (due to iodine deficiency, use of drugs such as lithium, iodine, some contrast agents); infiltrative diseases of thyroid (amyloidosis, scleroderma); post-viral / postpartum thyroiditis. Secondary (central): pituitary or hypothalamic disease. 20

21 Iodine deficiency is one cause of hypothyroidism. However, studies are also showing that in the case of chronic autoimmune thyroiditis, the highest prevalence occurs in countries with the highest intake of iodine, such as the US and Japan. So, although iodine supplementation should be implemented to prevent and treat iodine-deficiency disorders, supplementation should be maintained at a safe level. 21

22 Soy - high soy consumers and users of isoflavone supplements can be at risk of thyroid disorders since soy isoflavones can damage thyroid function. This is actually a rare occurance. Smoking has a negative impact on thyroid function and can cause a 3 to 5 fold increase in the risk of all types of thyroid disease. Tap water - Standard water-treatment plants cannot remove the chemical perchlorate from the water supply. According to one researcher, "There is a statistical association between low-level contamination with ammonium perchlorate and elevated or abnormal thyroid function." Also, chlorine content in the water can displace the much-needed iodine. 22

23 Fluoride is an enzyme poison which accumulates in the body. Since the body can only eliminate 50% of its total fluoride intake, this build-up can cause harm to the thyroid by blocking the use of iodine. Pesticides - such as sumithrin (Anvil) and resmethrin (Scourge), are coming under considerable criticism for their adverse chronic effects on the thyroid. Family history of thyroid disease is a warning signal. Also a family history of depression, autoimmune disease, chronic fatigue or weight issues can signify thyroid problems. Radiation and X-Rays are known to cause damage to the thyroid and technicians should always cover the patient s throat. Stress is a factor in almost every kind of disease and can affect the thyroid. Pregnancy It is estimated that between 5-10% of all pregnancies will result in PPT (Postpartum Thyroiditis). Menopause hormonal changes during this period of a woman s life can wreak havoc on her thyroid. 23

24 Prevalence of hypothyroidism In iodine-replete communities, the prevalence of spontaneous hypothyroidism is between 1 % and 2 %, and it is more common in older women and ten times more common in women than in men. 24

25 Definition of Subclinical Hypothyroidism Patients with mild thyroid failure have mildly elevated TSH levels and normal T 3 and T 4 levels An isolated elevated TSH level in the setting of normal T 3 and T 4 levels Symptoms may be present or absent 25 Cooper DS. N Engl J Med. 2001;345:

26 Subclinical Hypothyroidism Prevalence Worldwide prevalence between 1% and 10% of the population worldwide. Highest rates are in women older than 60 years of age Over the age of 74, 16% of men and 21% of women have the disorder 26 Cooper DS. N Engl J Med. 2001;345:

27 Impact of Maternal Hypothyroidism on Subsequent Neuropsychological Development of Offspring Undiagnosed hypothyroidism in pregnant women may adversely affect fetuses Maternal hypothyroidism is associated with decreased IQ in newborns Screening for hypothyroidism before or very early in pregnancy may be warranted 27 Haddow JE, et al. N Engl J Med. 1999;341:

28 Thyrotoxicosis and Hyperthyroidism Definitions Thyrotoxicosis The clinical syndrome of hypermetabolism that results when the serum concentrations of free T 4, T 3, or both are increased Hyperthyroidism Sustained increases in thyroid hormone biosynthesis and secretion by the thyroid gland The 2 terms are not synonymous 2% of women and 0.2% of men Many patients with thyrotoxicosis have hyperthyroidism, others do not, such as those who have thyrotoxicosis from excess intake of exogenous thyroid hormone. Braverman LE, et al. Werner & Ingbar s The Thyroid. A Fundamental 28 and Clinical Text. 8th ed

29 Hyperthyroidism Underlying Causes Signs and symptoms can be caused by any disorder that results in an increase in circulation of thyroid hormone Toxic diffuse goiter (Graves disease) Toxic uninodular or multinodular goiter Painful subacute thyroiditis Silent thyroiditis Toxic adenoma Iodine and iodine-containing drugs and radiographic contrast agents Trophoblastic disease, including hydatidiform mole Exogenous thyroid hormone ingestion The most common cause of hyperthyroidism Accounts for 60% to 90% of cases Incidence in the United States estimated at 0.02% to 0.4% of the population Affects more females than males, especially in the reproductive age range 29

Hyperthyroidism S&S Heat intolerance Hyperactivity, irritability Weight loss (normal to increased appetite) diarrhea Tremor, Palpitations Diaphoresis (sweating) Lid

30 Hyperthyroidism S&S Heat intolerance Hyperactivity, irritability Weight loss (normal to increased appetite) diarrhea Tremor, Palpitations Diaphoresis (sweating) Lid retraction & Lid Lag (thyroid stare) proptosis menstrual irregularity Goitre Tachcardia 1. Eyes 2.Tachycardia 3. Tremor 4. Brisk tendon reflexes 5. Increased growth and bone age 30

31 31

32 Iodine Deficiency Disorders (IDD) 1. Endemic goiter 2. Endemic cretinism 3. Intellectual disability 4. Growth retardation 5. Neonatal hypothyroidism 6. Increased early and late pregnancy loss 7. Increased perinatal and infant mortality 32

33 Iodine Deficiency Disorder IDD severe to cause goiter in 30% or more of population Correction of iodine deficiency before pregnancy Severe hypothyroidism in infancy termed cretinism Maternal hypothyroidism is a factor contributing to cretinism Most common preventable cause of mental deficits in the world The WHO estimated that 20 million people in the world had varying degrees of preventable brain damage due to effects of iodine deficiency on fetal brain development Population at risk for IDD caused by low levels of iodine in the soil was estimated to be 1 billion, approximately 20% of whom have goiter 33

34 The spectrum of iodine deficiency disorders (IDD) The most critical period is from the second trimester of pregnancy to the third year after birth 34

35 Neonatal Hyperthyroidism Transient Mother high TSI Persistent Family History of Graves 35

36 36

37 Thyroid Diseases risk factors Gender Age Personal History - Autoimmune Disease Personal History - Pregnancy Family History Thyroid Surgery Cigarette Smoking Goitrogenic Foods Iodine Exposure/Intake Iodine Deficiency Medications and Treatments Medical Radiation Exposure Environmental Radiation Exposure Medical Tests Involving Radiographic Contrast Agents/Contrast Dye Neck Surgery/Trauma Surgical Antiseptic Exposure Other Factors: Stress, left handed, ambidextrous or prematurely gray 37

38 Thyroid Diseases risk factors cont.. Gender Women face a greater risk of developing thyroid disease than men. 6 to 8 times more likely than men to develop a thyroid condition. Age Being 50 and above increases the risk of thyroid disease for both men and women. By age 60, as many as 17 % of women and 9 % of men have an underactive thyroid. Personal History - Autoimmune Disease A personal history of thyroid disease increases your current risk for developing thyroid disease. For example, A personal history of any autoimmune disease slightly increases your risk of developing an autoimmune thyroid disease such as Hashimoto's disease or Graves' disease. 38

39 Thyroid Diseases risk factors cont.. Personal History - Pregnancy Nearly one out of 50 women is diagnosed with hypothyroidism during pregnancy. Six out of every 100 miscarriages are associated with thyroid hormone deficiencies during pregnancy. Family History A family history of thyroid disease increases your risk for developing thyroid disease. The risk is slightly greater if you have a first-degree female relative (mother, sister, daughter) with thyroid disease. 39

40 Thyroid Diseases risk factors cont.. Thyroid Surgery Surgical removal of all or part of the thyroid usually results in hypothyroidism -- an underactive thyroid. Radioactive Iodine Treatment (RAI) to the thyroid - which is used to treat Graves' disease/hyperthyroidism and is often used as part of thyroid cancer treatment after surgery - typically results in hypothyroidism. Cigarette Smoking Smoking increases the risk of developing autoimmune thyroid disease.. Researchers have found that smoking may increase the risk, severity and side effects of hypothyroidism 40

41 Thyroid Diseases risk factors cont.. Goitrogenic Foods Some foods - when eaten raw and in large quantities -- naturally contain chemicals that can promote goiter (enlarged thyroid) and cause hypothyroidism in some people. brussel sprouts broccoli cabbage cauliflower kale kohlrabi millet radishes rutabagas soy turnips بروسل براعم بروكلي الكرنب قرنبيط كرنب الكرنب السلقي الدخن فجل اللفت الصويا فجل 41

42 Thyroid Diseases risk factors cont.. Iodine Exposure/Intake Use of iodine or herbal supplements containing iodine, in pill or liquid form, by people who are iodine sufficient increases the risk of autoimmune thyroid disease and hypothyroidism, and, less commonly, hyperthyroidism or thyrotoxicosis. Iodine Deficiency Lack of sufficient iodine increases the risk of hypothyroidism and goiter. 42

43 Thyroid Diseases risk factors cont.. Medications and Treatments Certain medical treatments and drugs such as Interferon Beta-1b, Interleukin-4, immunosuppressants, antiretrovirals, monoclonal antibody (Campath-1H), bone marrow transplant, Lithium, and amiodarone (Cordarone), among others increase the risk of developing an underactive thyroid. Medical Radiation Exposure Exposure of the neck area to radiation, such as in medical treatments for head or neck cancer, increases the risk of autoimmune thyroid disease, and thyroid cancer. Environmental Radiation Exposure Accidental radiation exposure in the environment, like that experienced by people who were exposed to radiation-contaminated air, food, milk and water after the 1986 Chernobyl nuclear accident, also increases the risk of autoimmune thyroid disease and thyroid cancer. 43

44 44

45 Thyroid Diseases risk factors cont.. Other Factors Other research points to, but does not definitely establish, an increased risk of autoimmune disease -- including autoimmune thyroid disease -- in people who are left-handed, ambidextrous or prematurely gray. It's thought that these traits may be found on a particular gene that is also shared by certain autoimmune tendencies. Stress Major stress - emotional or physical (like a car accident) is considered an environmental factor for autoimmune thyroid disease. 45

46 Thyroid Diseases risk factors cont.. While almost anyone can develop thyroid disease, individuals fitting one or more of the following descriptions are at an increased risk: Women over the age of 60 Individuals with a preexisting autoimmune disorder Individuals with close family member that has been diagnosed with an autoimmune disease You have been recently treated with radioactive iodine or received radiation treatment Patients who have undergone a previous thyroid procedure or partial thyroidectomy Have been pregnant or given birth with in the last 6 8 months 46

47 Thyroid Diseases risk factors cont.. Risk Factors for Thyroid Disease personal history of autoimmune disease (i.e. Type I Diabetes) family history of thyroid disease personal history of neck irradiation drug therapies (lithium, amiodarone) women > 50 years of age women in the period of up to 6 months postpartum 47

48 Thyroid Function: blood tests TSH Free T4 (thyroxine) Free T3 (triiodothyronine) mu/l pm pm 48

49 Principal of newborn screening Aim is to identify affected infants before development of clinical signs Objective : Eradication of MR secondary to CH The earlier dx the better IQ 49

50 Definitions Screening Technique cord blood TSH Screening: search for a disease in a large unselected population PKU Congenital hypothyroidism blood spot in a filter paper obtained by heel brick for TSH /T4 50

52 > screening < screening 52

53 Congenital Hypothyroidism 53

54 54 A Color Atlas of Endocrinology p51 Neonatal hyperthyroidism born to mother with Graves disease

55 55

56 Hyperthyroid Eye Disease 56

57 57

58 Phenylketonuria What is PKU? PKU Genogram it is an Autosomal recessive inborn error of metabolism found on the 12th chromosome Causing an inherited metabolic disease that passes through families It is rare condition characterized by the deficiency in the enzyme (Phenylalanine Hydroxylase). Normally: phenylalanine tyrosine by liver enzyme phenylalanine hydroxylase (PAH) The baby is born lacking the ability to break down phenylalanine into tyrosine. 58

59 Incidence of PKU 1 out of 50 people are carriers of this defective gene; causing incidence of 1 in 10,000 to 1 in 15,000 births. Mostly those of northern European background. Asians, and Africans are less commonly affected. 59

blood to test if the trait is present on the 12th

60 Diagnosis of PKU Nearly all cases of PKU are found in newborns screening tests after birth A small sample of blood to test if the trait is present on the 12th chromosome. A heel stick is done and then collected on special blotter paper 60

61 Diagnostic findings Normal: umol/l or 1.6mg/dl PAH Deficient: Mild: umol/l Classical: > 1200 umol/l 61

62 Symptoms of PKU Vomiting Skin Rashes Hyperactivity Small head size Mental Retardation Behavioral and social problems Seizures tremors or jerking movements A musty odor in the skin, breath or urine caused by too much Phenylketonuria 62

63 Prevention of PKU Patients are highly recommend to have strong relationship with physician - Genetic counseling is important especially to newly married and diagnosed couples An Enzyme Assay can determine if parents carry defective gene Chorionic villus Sampling - screen unborn baby for possibility of PKU 63

64 Newborn Screening A state mandated public health program that begins with a heel poke for every baby before hospital discharge First screen must be taken hours of life regardless of feeding status or weight 64 Blood Sample on Guthrie Filter Paper Card

65 Why Salt? Possible: technologically easy to add iodine to salt Cheap: 0.02 US$ per person per year Safe: salt consumption 5-15 gr/day; iodine added does not exceed maximum limit and is still enough to meet daily requirement Available to all: salt is everywhere Affordable for all: salt is cheap Ideal: Table + Food + Animal 65

66 Recommended Screening for Disorders of Thyroid Function Population Testing Frequency Men Women Pregnant women Every 5 years beginning at 35 years of age Every 5 years beginning at 35 years of age As soon as possible after conception; up to 3 months after giving birth Patients >60 years of age Once a year The Endocrine Society Web site. Available at: Accessed April 17, Loyola University New Orleans Web site. Available at: Accessed April 17, 2003.

67 PRACTICE POINTS Thyroid disorders are among the most prevalent of medical disorders, especially in women; therefore the possibility of thyroid disease should be included in the differential diagnosis of a patient especially in the presence of non-specific symptoms. Assessment of TSH and T4 should provide definitive evidence of overt / subclinical thyroid dysfunction. In subclinical hypothyroidism, the higher the level of TSH, the more likely the patient is to develop overt hypothyroidism over time. Patients with evidence of subclinical hyperthyroidism require regular clinical and laboratory follow-up. 67

Diseases of thyroid & parathyroid glands (1 of 2)

Diseases of thyroid & parathyroid glands (1 of 2) Thyroid diseases Thyrotoxicosis Hypothyroidism Thyroiditis Graves disease Goiters Neoplasms Chronic Lymphocytic (Hashimoto) Thyroiditis Subacute Granulomatous