As the name indicates, it refers to a lack of iodine in the body. Iodine is an important trace element that is a necessary constituent of the thyroid hormones Triiodothyronine and Thyroxine. The body cannot produce iodine. Naturally, it needs to be obtained from the diet. In places where there is very little or no iodine present in the diet, people may suffer from various disorders caused by iodine deficiency, such as goiter and cretinism. Insufficient amounts of iodine leads to the enlargement of thyroid gland, hypothyroidism, mental retardation as well as developmental delays in newborns and young children.

The disease is also referred to as Iodine deficiency disorder (IDD).

Iodine Deficiency Epidemiology

The disease has been noticed in more than 2 million people across the world. Certain parts of the world are more vulnerable to this disorder due to the natural deficiency and lack of iodine. These include places like South-East Asia, Africa and Western Pacific. Various parts of China and Russia are also highly affected. Patients of all ages have been found to be affected by this disorder. No racial predilection of this condition exists. After the age of 10 years, the rate of occurrence of goiter is somewhat higher in females than in males. Out of the 2.2 billion worldwide populations who are at a risk for developing the condition, 30 to 70% have goiter and around 1 to 10% have cretinism.

Iodine Deficiency Causes

Iodine is a chemical component that needs to be substituted in the diet as the body itself cannot naturally produce it. However, a dearth of iodine in the diet can lead to the development of iodine deficiency. A number of other factors can also lead to such a deficiency; these include congenital factors where the iodine deficiency of the mother is passed on to the newborn child. Consumption of alcohol, tobacco or hormonal products may also lead to deficiency of iodine.

Iodine Deficiency Risk Factors

A number of factors may increase the propensity of developing this disorder. These include the following:

Picture 1 – Iodine Deficiency

• Alcohol
• Pregnancy
• Perchlorates
• Thiocyanates
• Smoking tobacco
• Low dietary iodine
• Oral contraceptives
• Selenium deficiency
• Exposure to radiation
• Gender, with a higher rate of occurrence in women
• Age (for the different forms of iodine deficiency developing at different ages)
• Increased intake or increased levels of goitrogens in the plasma, such as calcium

Iodine Deficiency Symptoms

Deficiency of iodine leads to improper development of the thyroid gland, which eventually causes a number of symptoms, such as:

Goiter

Lower amounts of Thyroxine in the plasma give rise to higher quantities of the thyroid stimulating hormone or TSH. This causes stimulation of the thyroid gland that leads to the increase of many biochemical processes. This cellular growth along with proliferation can lead to hyperplasia or the characteristic swelling of thyroid gland; a condition commonly referred to as goiter. In cases of mild iodine deficiency, the levels of Triiodiothyronine or T₃ can get raised in presence of lower amounts of Levothyroxine, as more quantities of Levothyroxine is converted to Triiodothyronine as a sort of compensation. Some of the patients may also exhibit goiter without elevated levels of TSH.

Cretinism

Cretinism is said to be the most extreme form of IDD. It is commonly associated with lack of iodine and goiter, and is characterized by:

• Deaf-mutism
• Stunted growth
• Squint
• Mental deficiency
• Disorders of gait and stance
• Hypothyroidism

The relation between the goitre parents and the mentally retarded children was first pointed out by Paracelsus.

Cretinism can be further divided into the neurologic and the myxedematous subtypes. Both these types clinically overlap each other to some degree. Myxedematous cretinism is believed to be caused by hypothyroidism and iodine deficiency in the fetus around the time of late pregnancy or during the neonatal period. It leads to goiter, short stature, mental retardation and hypothyroidism. Cretinism can also be held responsible to cause a significant drop in the IQ levels of the patients throughout the world.

Hypothyroidism

In places where only very little amounts of iodine is present in the diet, such as in typically remote inland localities and semiarid equatorial climates where marine foods are not consumed, iodine deficiency can give rise to hypothyroidism, the signs of which include goiter, extreme fatigue, mental slowing, weight gain, depression, and also lower basal body temperatures. Individuals suffering from severe iodine deficiency may also complain of dry skin, cold intolerance, constipation as well as diseases of oral and the salivary glands.

Mental Retardation

Iodine deficiency is the principal cause of avoidable mental retardation worldwide. Although the children born of mothers from the iodine-deficient areas may come up with normal results of thyroid function tests, they may still exhibit lower memory and language performance. Mental retardation caused by iodine deficiency can get exaggerated due to concomitant deficiencies of Vitamin A or selenium. Children who are especially sensitive to postnatal fluctuations of iodine intake are at a greater risk of having poor mental as well as psychomotor development.

Other signs and symptoms of this disorder include:

• Autism
• Anxiety
• Paleness
• Joint pains
• Strabismus
• Bradycardia
• Constipation
• Osteoporosis
• Muscle cramps
• Water retention
• Muscle hypotonia
• Lowered immunity
• Slowed metabolism
• Fetal hypothyroidism
• Difficulty in breathing
• Emotional disturbance
• Slowed brain functions
• Carpal tunnel syndrome
• Deepening of voice
• Difficulty while swallowing
• Abnormal menstrual cycles
• Improper thyroid functions
• Compromised organ functions
• Soreness, cysts and heaviness in the breasts

Iodine Deficiency Symptoms in Women

There are a number of symptoms that are typically seen in women suffering from a lack of iodine. These include:

• Acne
• Hives
• Coma
• Ataxia
• Apnea
• Lupus
• Vitiligo
• Vertigo
• Pruritis
• Edema
• Autism
• Anemia
• Nausea
• Myalgia
• Asthma
• Rhinitis
• Arthritis
• Retinitis
• Eczema
• Fibrosis
• Tinnitus
• Diarrhea
• Epilepsy
• Urticaria
• Hepatitis
• Allergies
• Seizures
• Alopecia
• Infertility
• Asthenia
• Migraine
• Polyurea
• Irritability
• Stillbirths
• Cachexia
• Cataracts
• Dizziness
• Hair loss
• Dementia
• Gingivitis
• Arthralgia
• Headache
• Back Pain
• Dry Mouth
• Glaucoma
• Chest pain
• Dyspepsia
• Polydipsia
• Dystrophy
• Myotrophy
• Depression
• Blind Spots
• Weak Pulse
• Thrombosis
• Hoarseness
• Hemorrhage
• Eosinophilia
• Constipation
• Otosclerosis
• Cold shivers
• Birth defects
• Lung cancer
• Scleroderma
• Pyelocystitis
• Convulsions
• Mouth Sores
• Fibromyalgia
• Osteoporosis
• Hearing Loss
• Osteoarthritis
• Hypertension
• Restlessness
• Cholelithiasis
• Optic Neuritis
• Sluggishness
• Miscarriages
• Fibrosarcoma
• Breast Cancer
• Gastric Ulcers
• Kidney Failure
• Telangiectasia
• Schizophrenia
• Osteosarcoma
• Mood changes
• Osteosarcoma
• Uterine Cancer
• Lack of Energy
• Thyroid Cancer
• Muscle Cramps
• Heart Disorders
• Atherosclerosis
• Dental crowding
• Polyneuropathy
• Sleep Disorders
• Mottling of teeth
• Sinus Infections
• Loss of appetite
• Down syndrome
• Muscle Stiffness
• Uterine Bleeding
• Ulcerative Colitis
• Diabetes Mellitus
• Vaginal Bleeding
• Multiple Sclerosis
• Heart palpitations
• Pre-term delivery
• Sensitivity to light
• Slipped epiphysis
• Pulmonary edema
• Aorta Calcification
• Diabetes Insipidus
• Premature Delivery
• Inner Ear Disorders
• Smaller dental arch
• Abnormal Sweating
• Anaphylactic Shock
• Shortness of breath
• Visual Disturbances
• Parkinson’s disease
• Alzheimer’s disease
• Excessive sleepiness
• Giant Cell Formation
• Lack of coordination
• Collagen Breakdown
• Behavioral Problems
• Dental Abnormalities
• Hyperparathyroidism
• Swallowing difficulties
• Delayed teeth eruption
• Problems with memory
• Ankylosing spondylitis
• Loss of consciousness
• Demyelinizing diseases
• Muscoskeletal diseases
• Carpal Tunnel Syndrome
• Monisiliasis (Candidasis)
• Respiratory Complications
• Chronic Fatigue Syndrome
• Ear, eye and nose disorders
• Inflammatory Bowel Disease
• Gastro-intestinal disturbances
• Alterations of the vas deferens
• Changes in the blood pressure
• Oral Squamous Cell Carcinoma
• ADHD and/or learning disorders
• Decrease in Testosterone levels
• Early or delayed onset of puberty
• Problems with hearing and speech
• Swelling of the face or angioedema
• Brittled, lined or grooved fingernails
• Crying without any apparent reason
• Disturbances in the body temperature
• Dental enamel becoming more porous
• Difficulty in focusing and concentration

Iodine Deficiency Diagnosis

While diagnosing IDD, a doctor is likely to first conduct a thorough physical checkup and ask the patient questions about his or her general health. He or she will then recommend certain tests to evaluate the status of iodine deficiency in the patient. Although there are no tests to conclusively prove that an individual is having a deficiency of this element, the following tests are usually conducted to check iodine levels:

• Histological tests
• Dietary questionnaires
• Urinary iodine concentration tests
• Assessment of the thyroid volume
• Ultrasonograms to evaluate thyroid sizes
• Dried whole-blood spot thyroglobulin (Tg) level tests

The results obtained from the thyroid function studies generally indicate signs of mild iodine insufficiencies. In patients having iodine deficiency and euthyroidism, the serum TSH levels can range from being normal to being increased. The T3 levels can be either normal or somewhat elevated and the T4 levels might be normal or reduced. Hypothyroidism develops only in very elevated serum TSH levels and in reduced T₄ and T₃ levels.

Measurement of dried whole-blood spot level of Tg can help in understanding thyroid functions in children. It can also act as a sensitive early measurement of iodine repletion compared to serum thyroxine (T₄) or TSH.

A 24-hour urine iodine collection can be an effective test in evaluating iodine levels, as almost 90% of the ingested iodine gets excreted in urine. If conducting this test is not feasible, a random urine iodine-to-creatinine ratio test can alternatively be carried out.

Iodine Deficiency Differential Diagnosis

A number of conditions are manifested by signs and symptoms similar to that of IDD. Hence while trying to determine the diagnosis of this disorder; it should be differentiated from such similar conditions in order to facilitate better clinical management. The differential diagnoses of IDD include health ailments such as:

Picture 2 – Iodine Deficiency Image

• Infertility
• Thyroiditis
• Depression
• Constipation
• Hypothermia
• Dysmenorrhea
• Thyroid nodule
• Hypothyroidism
• Pericardial effusion
• Erectile Dysfunction
• Hurthle cell carcinoma
• De Quervain Thyroiditis
• Euthyroid sick syndrome
• Papillary thyroid carcinoma
• Follicular thyroid carcinoma
• Anaplastic thyroid carcinoma
• Rare forms of tumors of mediastinum
• Thyroxine-binding globulin deficiency
• Endocrine and/or mesenchymal lymphomas
• Nontoxic, toxic nodular or lithium-induced goiter

Iodine Deficiency Treatment

IDD is generally treated by supplementing iodine with food substances. Mild cases can be treated with increasing the quantities of iodized salt in daily food consumption of patients. It can also be done by adding egg yolks, saltwater fishes or more milk in the regular diet. Iodized salt can offer amounts of iodine appropriately needed by the patients. For an animal product and/or salt restricted diet, the patients can be advised to have sea vegetables like hijiki, kelp, dulse, and nori as they are excellent sources of iodine. In a non-pregnant adult, 150 µg/d is generally sufficient for sustaining normal thyroid functions. However, women might need additional amounts of iodine. For this, the recommended dosage of daily iodine intake is around 150 to 300 µg/d. If a patient is exhibiting compressive symptoms due to a large goiter, a thyroidectomy procedure may be required to be carried out.

Iodine Deficiency Complications 1

Treatment for this disease may ultimately lead to hyperthyroidism, especially in patients who are above 45 years of age. This occurs due to the hyperfunctioning of long-standing iodine-deficient goiters in these patients.

Iodine Deficiency Prevention

The condition can be effectively prevented on population levels by iodization of the food products or water supply. This can be practically done by the iodization of salt, i.e., by adding chemical compounds like sodium iodate, sodium iodide, potassium iodide and/or potassium iodate. Alternatively, one can increase the amounts of iodine in their daily diet by consuming iodine-rich foods such as:

• Cow’s milk
• Cheese
• Eggs
• Ice cream
• Frozen yogurt
• Iodized table salt
• Iodine-containing multivitamins
• Saltwater fishes
• Shellfish
• Seaweeds
• Soy sauce
• Soy milk
• Yogurt

Iodine Deficiency Prognosis

Iodine supplementation can reduce the size of goiters caused by deficiency of iodine in pregnant women and very young children. However, the long-standing goiters occurring due to iodine deficiency generally responds with a small shrinkage after the iodine supplementation, and the patients are at a considerable risk of developing hyperthyroidism.

References:

http://en.wikipedia.org/wiki/Iodine_deficiency

http://www.thyroid.org/iodine-deficiency/

http://emedicine.medscape.com/article/122714-overview

http://www.uptodate.com/contents/iodine-deficiency-disorders

http://www.3fatchicks.com/4-symptoms-of-an-iodine-deficiency/

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