HYPOTHYROIDISM

Question 1

Essentials of diagnosis of a patient with Hypothyroidism.

Answer 1

(1) Weakness, cold intolerance, constipation, depression, menorrhagia,
hoarseness, dry skin, bradycardia
(2) Delayed return of deep tendon reflexes
(3) Serum free tetraiodothyronine aka thyroxine (T4) low
(4) Thyroid-stimulating hormone (TSH) elevated in primary hypothyroidism

Question 2

General Considerations of a patient with Hypothyroidism.

Answer 2

(1) Primary hypothyroidism is due to thyroid gland disease
(2) Secondary hypothyroidism is due to lack of pituitary TSH
(3) Maternal hypothyroidism during pregnancy results in cognitive impairment in child
(a) Generally need to increase dose ofthyroid replacement hormone
(levothyroxine) by 30%

Question 3

(4) Causes of hypothyroidism with goiter

Answer 3

(a) Autoimmune:
1) Hashimoto’s Disease
2) Thyroiditis
(b) Subacute (de Quervain’s thyroiditis) (after initial hyperthyroidism)
(c) Iodine deficiency (seen in developing countries)
(d) Genetic thyroid enzyme defects
(e) Hepatitis C
(f) Drugs:
1) Lithium, amiodarone, propylthiouracil, methimazole,
phenylbutazone, sulfonamides, interferon-ƒÑ or ƒÒƒn
ƒn
(g) Food goitrogens in iodide-deficient areas
(h) Peripheral resistance to thyroid hormone
(i) Infiltrating diseases

Question 4

Causes of hypothyroidism without goiter

Answer 4

(a) Thyroid surgery, irradiation, or radioiodine treatment
(b) Deficient pituitary TSH
(c) Severe illness
(d) Drugs
1) Lithium
2) Amiodarone
3) Propylthiouracil
4) Methimazole
5) Phenylbutazone
6) Sulfonamides
7) Interferon-a & b
8) Iodine
(e) Radiation therapy to the head-neck-chest-shoulder region can cause
hypothyroidism with or without goiter or thyroid cancer many years later
(f) “Subclinical” hypothyroidism, i.e., clinically euthyroid individual with
high TSH, normal T4, occurs commonly in elderly women (~10%
incidence)
(g) Amiodarone, due to high iodine content, causes clinical hypothyroidism in ~8%
(h) High iodine intake from other sources may also cause hypothyroidism,
especially in those with underlying lymphocytic thyroiditis
(i) Myxedema is caused by interstitial accumulation of hydrophilic
mucopolysaccharides, leading to fluid retention and lymphedema

Question 5

Clinical Findings of a patient with Hypothyroidism.

Early symptoms

Answer 5

(a) Fatigue, lethargy, weakness
(b) Arthralgias, myalgias, muscle cramps
(c) Cold intolerance
(d) Difficulty concentrating
(e) Constipation
(f) Dry skin
(g) Headache
(h) Weight gain
(i) Menorrhagia

Question 6

Clinical Findings of a patient with Hypothyroidism.

Late symptoms

Answer 6

(a) Slow speech
(b) Peripheral edema
(c) Pallor
(d) Hoarseness
(e) Decreased senses of taste, smell, and hearing
(f) Dyspnea
(g) Absent sweating
(h) Amenorrhea or menorrhagia
(i) Galactorrhea

Question 7

Clinical Findings of a patient with Hypothyroidism.

Early signs

Answer 7

(a) Thin, brittle nails
(b) Thinning of hair
(c) Pallor
(d) Poor turgor of mucosa
(e) Delayed return of deep tendon reflexes

Question 8

Clinical Findings of a patient with Hypothyroidism.

Late signs

Answer 8

(a) Goiter
(b) Puffiness of face and eyelids
(c) Thinning of outer eyebrows
(d) Tongue thickening
(e) Hard pitting edema
(f) Pleural, peritoneal, pericardial, and joint effusions

Question 9

Clinical Findings of a patient with Hypothyroidism.

Myxedema coma

Answer 9

(a) Hypothermia, hypotension, hypoventilation, hypoxia, hypercapnia,
hyponatremia
(b) Convulsions and abnormal CNS signs
(c) Often induced by
1) Underlying infection
2) Cardiac, respiratory, or CNS illness
3) Cold exposure
4) Drug use
5) Cardiac enlargement due to pericardial effusion, bradycardia
6) Hypothermia

Question 10

Lab/imaging findings of a patient with Hypothyroidism.

Answer 10

(1) Serum TSH is increased in primary hypothyroidism but low or normal in
secondary hypothyroidism (pituitary insufficiency)
(2) Free T4 may be low or low normal
(3) Serum triiodothyronine (T3) is not a good test for routine hypothyroidism
(4) Serum cholesterol, triglycerides, liver enzymes, creatine kinase, prolactin increased
(5) Hyponatremia occurs due to impaired renal tubular sodium reabsorption
(6) Hypoglycemia
(7) Anemia (with normal or increased mean corpuscular volume)

Question 11

Treatment of a patient with Hypothyroidism.

Answer 11

(1) Levothyroxine (T4)
(a) For adult hypothyroidism, levothyroxine is started at 25 – 75 mcg/day
administered orally.
(b) Starting doses and dose changes may differ with individual patients based
upon age, the presence of cardiovascular disease, the development of
tolerance (reduced effectiveness with continued use), side effects to the
medication, and blood levels of thyroid hormone.
(c) Thyroid function tests should be repeated every 4 to 6 weeks for
medication titration until TSH is at goal.

Question 12

Disposition of a patient with Hypothyroidism.

Answer 12

(1) MEDEVAC
(a) Depends on signs and symptoms
(b) May retain if no major issues.

Question 13

Complications of a patient with Hypothyroidism.

Answer 13

(1) Angina pectoris, congestive heart failure and cardiac dysrhythmias may be precipitated by too rapid thyroid replacement
(2) Increased susceptibility to infection
(3) Megacolon in long-standing hypothyroidism
(4) Organic psychoses with paranoid delusions (“myxedema madness”)
(5) Adrenal crisis precipitated by thyroid replacement