Thyroid Disorders: Hyperthyroidism, Hypothyroidism, and Related Conditions

Hyperthyroidism (Excessive Production)

• Elevated thyroid hormone
• Most T3 & T4 are bound to TBG, thus inactive
• Free T3 & T4 are active
• T3 is more active than T4

• (Graves’ disease, Toxic Nodular Goiter, Hasitoxicosis)
• High T3 + T4, Low TSH
• Increased autonomous production

• (Pituitary adenoma)
• Amiodarone can cause it
• High T3 & T4, High TSH
• Elevated TSH is the cause (e.g., Pituitary Adenoma)

• Increased metabolism, fatigue
• Nervousness
• Tremor
• Increased appetite
• Palpitations
• Warm & moist skin
• Hypercalcemia (thyroid hormone + osteoclast activity)
• Stress
• Feeling warm
• Weight loss
• Increased heart rate
• Diarrhea
• Psychological problems (fear & irritability)

• Initial tests: TSH, T3, T4

• Primary: Low TSH, High T3 & T4
• Secondary: High TSH, T3, T4
• Pheochromocytoma: Tumor of the adrenal gland producing norepinephrine, leading to high blood pressure

Graves’ Disease

Toxic Nodular Goiter

• Most common cause of hyperthyroidism
• Autoimmune: antibodies act as agonists for hormone production
• Can cause eye problems

• Hyperthyroidism signs
• Physical exam: nodule on the thyroid

• Increased heart rate
• Warm, moist skin
• Tremor
• Goiter
• Eye pain
• Exophthalmos (eye pulled back due to muscle infiltration)
• Pretibial edema

• Clinical exam
• TSH levels
• Radioactive iodine scan (definitive) = nodule
• Differential diagnosis from Graves’: Graves’ has no nodule

• TSH level, T3, T4 (TSH low, T3 & T4 high)
• Serology: thyroid-stimulating immunoglobulin (most accurate/definitive)
• CBC: normocytic anemia
• CMP: hypercalcemia (T3 increases osteoclast activity)
• Ultrasound + iodine scan

• For symptoms: propranolol
• Nodular goiter: radioactive iodine ablation (removal of nodules)
• Biopsy is used only if TSH is normal or patient doesn’t have hyperthyroid symptoms

• Direct: methimazole or PTU
• Symptomatic: propranolol (beta-blocker)
• Radioiodine ablation (except in pregnancy) (destroys thyroid gland)

Thyroiditis (Hyperthyroidism)

• Subacute (Painful)
• Lymphocytic
• Hashimoto’s

• Like primary hyperthyroidism
• Subacute: addition of pain, painful goiter
• Exophthalmos and visual problems are not present as in Graves’

• TSH level/T3/T4
• Serology for TSH
• RAIU scan (uptake poor because thyroid gland is damaged)

• Cause: virus
• Pain in neck
• Goiter, enlarged thyroid

• Starts with hyperthyroidism, then progresses to hypothyroidism

• ESR high
• TSH level will indicate the phase
• RAIU poor

• Symptomatic treatment
• Thyroid inflammation: prednisone
• Pain: aspirin
• Hyperthyroid symptoms: propranolol
• Self-limiting

• Autoimmune lymphocytic inflammation of thyroid
• Specific antibodies
• Most common cause of hypothyroidism

• Painless
• Enlarged goiter (not necessarily symmetric)
• Hypothyroid symptoms are most prominent

• TSH up, T3 & T4 low
• Anti-TPO & Anti-TG test (specific)

• Replacement of T3 + T4 = levothyroxine
• Check for nodule development

• Small, painless goiter
• Stages: hyperthyroidism → transient euthyroid → hypothyroidism → euthyroid

• TSH and RAIU according to stages [low TSH, low RAI… high TSH, low RAI]
• (Graves’, low TSH, high RAI)

• Only in case of thyrotoxicosis: propranolol (beta-blocker)

Factitious Hyperthyroidism

• Injection of thyroid hormone (external)
• No goiter (the thyroid gland isn’t working)

Radioactive Iodine Uptake Test (RAIU)

• Ultrasound + iodine → thyroid

• High T3 & T4
• Low TSH
• High iodine uptake (due to antibodies)
• Irony: iodine uptake is higher than normal

• Low T3 + T4
• Very poor visibility
• Almost nothing is visible (white)

• High T3 + T4
• Poor visibility
• Nothing is visible due to early stages of thyroiditis

Hypothyroidism

• Fatigue
• Lowered metabolism
• Tiredness
• Cold intolerance
• Heart problems
• Overweight
• Hair loss
• Slow tendon reflex
• Decreased appetite
• Galactorrhea
• Goiter (due to overcompensation)

• Decreased production by thyroid
• High TSH, low T3 & T4

• Hashimoto’s
• Medications (lithium, ASA)
• Any thyroiditis
• Iodine deficiency

• Low TSH, low T3 & T4

• Tumor mass effect

• Hypercholesterolemia
• Myxedema coma

Hashimoto’s Thyroiditis

• Autoimmune response against the thyroid
• Most common cause of hypothyroidism
• Mostly affects females
• Mediated by anti-TPO & anti-Tg antibodies

• Hypercholesterolemia
• Anemia of chronic disease (ACD)
• Hyponatremia

• Hypothyroid symptoms (weight gain, decreased appetite, cold intolerance, lethargy, menorrhagia)
• Enlarged thyroid (goiter)
• Bradycardia
• Cool & dry skin

• Clinical exam (goiter)
• Bradycardia
• Lab: TSH level (low), T3 + T4 (high)
• Serology: anti-TPO & anti-Tg

Hypercalcemia

• Ca > 10.5

• Drugs
• Hyperparathyroidism (high PTH)
• Malignancy

• Kidney stones
• Bone pain, fractures
• Psychiatric problems (calcium is important for neurons)
• Diabetes insipidus

1. Stabilize the patient
2. Get the PTH level:
   • If PTH is high = Primary hyperparathyroidism
   • Do 24-hour urine to distinguish it from familial hypocalcemic hypercalcemia
   • If PTH level is low → Malignancy

• Give fluids, followed by loop diuretics (furosemide)
• Bisphosphonates (alendronate, ibandronate)
• Acute episode: → IV calcitonin
• Parathyroidectomy

Hypocalcemia

• Ca < 9.0 mg/dl

• Thyroidectomy
• Vitamin D deficiency
• Renal failure

1. Stabilize the patient
2. Get the PTH level:
   • Low PTH = thyroidectomy or hypomagnesemia
   • High PTH = renal failure or vitamin D deficiency

• Neuronal hyperactivity
• Paresthesia
• Spasms
• Strong tendon reflexes
• Tetanus-like symptoms
• Chvostek’s sign (facial muscle spasm)

• Short term: calcium replacement with calcium gluconate
• Long term: calcium supplementation & vitamin D + fix underlying causes