Endocrinology Lect2,3 2003

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  • 1. ENDOCRINOLOGY THYROID DISORDERS
  • 2. Thyroid Disorders
    • Thyroid secretes thyroxine (T4) and small amount of triiofothyronine (T3).
    • @ 85% of T3 is converted from T4 in the tissues [ liver, muscle, and kidney]
    • The hormones are transported in the plasma almost entirely bound to thyroxine – binding globulin (TGB),pre-albumin, and albumin.
  • 3.
    • Production is stimulated by TSH in response to thyrotrophin – releasing hormone (TRH) and free T4 (FT4) --- has a negative effect on TSH release.
    •  FT4   TSH   TRH  thyroid production of T4 T3
  • 4. Hyperthyroidism
    • Caused by excess circulating T4 or T3
    • It is a common condition with a prevalence of 20/1000
    • Both male and females effected equally
    • 90% of cases are caused by:
      • Graves disease
      • Toxic multinodular goiter
      • Toxic solitary goiter
  • 5. Graves Disease
    • Onset may be insidious
    • Atrial fib is rare in young patient but occur in over 50% of males patient over 60 y/o
    • Results from IgG antibodies against the TSH – receptor
    • These antibodies are termed thyroid – stimulating antibodies (TSAb)
    • May be responsible for thyroid enlargement in this disease
  • 6.
    • The cardinal signs of Graves’ disease are:
      • Diffuse goiter
      • Vascular bruit can be heard over these goiters
      • Pretibial myxoedema
      • Tachycardia with a bounding pulse
      • Exophthalmos
      • Lid lag (usually on downward eye movement)
      • Lid retraction
      • Peri-orbital puffiness
      • Increased lacrimation
      • Conjunctival edema and ulceration
  • 7.
    • In the elderly a ‘masked’ hyperthyroidism may be found. If presentation of a 60 y/o with atrial fib, heart failure and weight loss
    • THINK HYPERTHYROIDISM!!!
    • Diagnosis is made clinically with confirmation by labs:
      • T3 and T4 and undetectable TSH levels
      • if a single nodule is suspected a thyroid scan may provide useful information
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  • 16. Treatment Options
    • Anti-thyroid drugs:
      • Carbimazole or methimazole followed by propylthiouracil
    • Beta-blocking drugs in the initial stages of management
    • Sub-total thyroidectomy
    • Radioactive iodine therapy
    • THE CHOICE OF THERAPY DEPENDS UPON A NUMBER OF FACTORS, ESPECIALLY THE PATIENTS AGE AND PREVIOUS HISTORY
  • 17.
    • Any questions?
  • 18. Hypothyroidism
    • Also known as Myxoedema results from the reduced secretion of T3 and T4 from the thyroid.
    • Hashimoto’s accounts for over 90% of the cases
    • Secondary hypothyroidism is much less common and is caused by pituitary disease [ absence of TSH leads to atrophy of thyroid gland]
  • 19. Clinical Presentation
    • Affects all the systems of the body, but the wide range of clinical features means that the diagnosis will be missed.
    • Dominant features in children are:
      • Reduction in growth velocity
      • Arrest of pubertal development
    • Clinical presentation in adults may vary greatly
  • 20.
    • Non – pitting edema [most marked on the skin of the eyelids and hands]  often associated with loss of eyebrow and scalp hair
    • Dryness of the skin
    • Reduced body hair
    • Bradycardia
    • Hypothermia
    • Pericardial and pleural effusions [ can occur and is life threatening]
  • 21.
    • Diagnosis is based on
      • Clinical suspicion
      • Prolonged relaxation time of peripheral reflexes
      • A low voltage EKG
      • Biochemical estimation of T4 and TSH
      • Thyroid Antibodies Assays
    • Causes of hypothyroidism
      • Autoimmune (most common Hashimotos)
      • Drugs induced (Lithium carbonate- which like iodide inhibits the release of thyroid hormones  goiter and hypothyroidism
  • 22. Treatment
    • In all cases is thyroxine
    • In older patients that present with or has a history of ischemic heart disease sudden increase in T4 levels has been known to cause M.I.s
    • Therefore, start on low dose (25ug) and increase very slowly[every 4 – 6 weeks] and should intensify management of anti – anginal therapy
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  • 27.
    • Any questions?
  • 28. What Are the Parathyroid Glands?
    • The parathyroid glands are four pea-sized glands located on the thyroid gland in the neck .
    • The parathyroid glands secrete parathyroid hormone (PTH), a substance that helps maintain the correct balance of calcium and phosphorous in the body.
    • PTH regulates release of the calcium from bone, absorption of calcium in the intestine, and excretion of calcium in the urine.
    • When the amount of calcium in the blood falls too low, the parathyroid glands secrete just enough PTH to restore the balance.
  • 29. Hyper-parathyroidism
    • If the glands secrete too much hormone,the balance is disrupted: blood calcium rises.
    • This condition of excessive calcium in the blood, called hypercalcemia
    • hypercalcemia is what usually signals the doctor that something may be wrong with the parathyroid glands
  • 30.
    • In 85 percent of people with this disorder, a benign tumor (adenoma) has formed on one of the parathyroid glands, causing it to become overactive.
    • In most other cases, the excess hormone comes from two or more enlarged parathyroid glands, a condition called hyperplasia.
    • Very rarely, hyperparathyroidism is caused by cancer of a parathyroid gland.
  • 31.
    • This excess PTH triggers the release of too much calcium into the bloodstream.
    • The bones may lose calcium, and too much calcium may be absorbed from food.
    • The levels of calcium may increase in the urine, causing kidney stones.
    • PTH also acts to lower blood phosphorous levels by increasing excretion of phosphorus in the urine
  • 32.
    • HPT is most often suspected when a high level of calcium is found in your blood on a routine blood test.
    • measuring the amount of PTH in your blood proves the diagnosis
  • 33. What Are the Symptoms of Hyperparathyroidism?
    • patients have severe symptoms, subtle ones, or none at all
    • When symptoms do appear, they are often mild and nonspecific, such as:
      • a feeling of weakness and fatigue,
      • depression,
      • or aches and pains
    • With more severe disease, a person may have:
      • a loss of appetite,
      • nausea, vomiting,
      • constipation,
      • confusion or impaired thinking and memory,
      • and increased thirst and urination
  • 34. How is HPT treated
    • Surgery to remove the growth in your neck almost always solves the problem.
    • The growth doesn't usually come back
    • Most of your symptoms will stop in the first month after surgery
    • For a short time after surgery, your blood calcium level may be too low
    • This problem is easily treated with medicine.
  • 35.
    • Although surgery is usually recommended for people with HPT (unless they have no symptoms), sometimes other medical problems make surgery too risky
    • If you don't have surgery, tests are needed from time to time to see if the disease is hurting your kidneys, bones or other body systems
    • Women who take estrogen after menopause are partly protected from the effects of HPT.
  • 36. Any questions?
  • 37. Hypoparathyroidism
    • is the clinical condition caused by a lack of parathyroid hormone
    • . Calcium levels in the blood fall, and phosphorus levels rise
    • The most common cause of hypoparathyroidism is injury to the parathyroid glands during head and neck surgery.
  • 38.
    • Rarely, hypoparathyroidism is a side effect of radioactive iodine treatment for hyperthyroidism
    • PTH secretion may be impaired when blood levels of the element magnesium are low or when blood pH is too high, a condition called metabolic alkalosis.
    • DiGeorge syndrome is a childhood disease in which hypoparathyroidism occurs due to congenital absence of the parathyroid glands
  • 39.
    • The incidence is about 4 out of 100,000 people.
    • Symptoms  
      • tingling of lips, hands and feet
      • muscle cramps
      • pain in face , legs and feet
      • abdominal pain
      • dry hair
      • brittle nails
      • dry, scaly skin
      • cataracts
      • weakened tooth enamel in children
      • muscle spasms called tetany
      • tetany can lead to spasms of the larynx with breathing difficulties
      • convulsions or seizures
  • 40.
    • Additional symptoms that may be associated with this disease:
    • menstruation, painful
    • hand or foot spasms
    • consciousness, decreased
    • teeth - delayed or absent formation
  • 41. Signs and tests    
    • low serum calcium level
    • elevated serum phosphorus
    • decreased serum parathyroid hormone level
    • decreased serum magnesium level (possible)
    • occasionally abnormal heart rhythms on ECG
  • 42. Treatment
    • The goal of treatment is to restore the calcium and associated mineral balance within the body
    • Oral calcium carbonate and Vitamin D supplements are usually life-long therapy
    • Blood levels require periodic monitoring to ensure proper dosage
    • . A high-calcium, low-phosphorous diet is recommended
    • Supportive care is necessary for an acute life-threatening attack or hypoparathyroid tetany (prolonged muscle contractions ).
  • 43.
    • Calcium is administered by intravenous infusion
    • Precautions are taken to prevent seizures or larynx spasms
    • Heart monitoring for abnormal rhythms is continued until the person is stabilized
    • When the life-threatening attack has been controlled, treatment continues with oral preparations.
  • 44. Complications
    • acute tetany, which can lead to respiratory obstruction requiring a tracheostomy
    • growth retardation, malformation of the teeth, and retarded mental development, which can occur if hypoparathyroidism develops in childhood
    • over treatment with Vitamin D and calcium, which can cause hypercalcemia (high blood calcium) and sometimes impaired kidney function
    • increased risk of pernicious anemia , Addison's disease , cataract development, and Parkinson's disease
  • 45. Prognosis
    • The probable outcome is good if the diagnosis is made early
    • Dental changes, cataracts , and brain calcifications are irreversible changes.
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