Hypothyroidism (Underactive Thyroid): Complications

The following are the major diseases or complications that may be contributed to by hypothyroidism (underactive thyroid):

Respiratory system (J00-J99)

Certain conditions originating in the perinatal period (P00-P96).

  • Neurologic damage in the fetus (unborn).

Endocrine, nutritional, and metabolic diseases (E00-E90).

  • Obesity (overweight)
  • Fetal/neonatal goiter
  • Hyperhomocysteinemia – increased concentrations of homocysteine (an amino acid) in the blood.
  • Hyperprolactinemia – pathological (abnormal) elevation of prolactin levels (most patients have normal PRL levels).
  • Hyperlipidemia/dyslipidemia (lipid metabolism disorders).
  • Hyperuricemia (elevation of uric acid levels in the blood) without signs of inflammatory arthritis (bone inflammation) or tophic gout
  • Hyponatremia (sodium deficiency)
  • Myxedema coma (hypothyroid coma) – usually stress-associated, such as trauma, infections such as pneumonia (pneumonia) or even psychological stress, as well as certain drugs such as sedatives (tranquilizers) or antidepressants (drugs against depression) triggered deterioration of the metabolic state with increased mortality (mortality rate).
  • Lipoprotein (a) increase
  • Goiter – thyroid volume above the sex- and age-specific normal range.

Cardiovascular system (I00-I99)

Musculoskeletal system (M00-M99)

Neoplasms – tumor diseases (C00-D48).

  • Colorectal carcinoma (colorectal cancer) – untreated hypothyroidism is associated with an increased risk of cancer (adjusted odds ratio (OR) of 1.16)

Ears – mastoid process (H60-H95).

  • Hypacusis (hearing loss)

Psyche – nervous system (F00-F99; G00-G99)

  • Delirium – acute state of confusion
  • Depression
  • Carpal tunnel syndrome (KTS) – compression syndrome (narrowing syndrome) of the median nerve in the region of the carpal canal.
  • Infantile retardation (if the mother does not receive hormone replacement during pregnancy).
  • Mild cognitive impairment (LKB; mild cognitive impairment, MCI; age forgetfulness; age-associated memory impairment (AAMI); age-associated memory impairment.
  • Male/female libido disorders
  • Alzheimer’s disease
  • Schizophrenia – children whose mothers had free T3 and T4 levels below the tenth percentile during pregnancy (odds ratio = 1.75, p = 0.002)

Pregnancy, childbirth, and puerperium (O00-O99).

  • Abortion (miscarriage)
  • Premature birth and stillbirth
  • Low birth weight
  • Preeclampsia – new-onset hypertension (high blood pressure) during pregnancy with proteinuria (excretion of protein in the urine; > 300 mg/24 h) after the 20th week of pregnancy.

Symptoms and abnormal clinical and laboratory findings not classified elsewhere (R00-R99).

  • Bradycardia – heartbeat too slow: < 60 beats per minute.
  • Failure to thrive/delayed growth and bone maturation (manifest, untreated, connatal or acquired hypothyroidism in childhood and adolescence)
  • Hypothermia (decreased body temperature).
  • Constipation (constipation)
  • Edema (water retention)
  • Growth retardation in children – retardation of growth with impaired bone maturation and ultimately short stature.
  • Wound healing slowed

Genitourinary system (kidneys, urinary tract – sex organs) (N00-N99)

  • Amenorrhea – no menstrual bleeding for> 90 days with an already established menstrual cycle (secondary amenorrhea).
  • Hypermenorrhea – bleeding is too heavy (> 80 ml); usually the affected person consumes more than five pads/tampons per day
  • Menorrhagia – bleeding is prolonged (> 6 days) and increased.
  • Oligomenorrhea – menstrual bleeding: interval between bleeding is > 35 days and ≤ 90 days.
  • Nephrotic syndrome – collective term for symptoms that occur in various diseases of the glomerulus (renal corpuscles); symptoms include: Proteinuria (increased excretion of protein in urine) with protein loss of more than 1 g/m²/body surface per day; Hypoproteinemia, peripheral edema (water retention) due to hypalbuminemia of < 2.5 g/dl in serum, hyperlipoproteinemia (lipid metabolism disorder) with LDL elevation.
  • Female sterility / male infertility disorder.

Further

  • Increased mortality/sterility rate due to.
    • Ischemic heart disease or death from heart disease (relative risk [RR]: 1.96, 95% confidence interval between 1.38 and 2.80)
    • Untreated and overtreated hypothyroidism: in which the duration of overtreatment (TSH suppression) had a stronger effect on mortality than the duration of no or inadequate treatment (TSH elevation)
      • Increased mortality (hazard ratio HR = 1.46) of untreated patients with hypothyroidism versus euthyroid controls (patients with normal thyroid function)
      • Mortality increase for each six-month period with elevated TSH (HR = 1.05).
      • Mortality increase when TSH was decreased on therapy (factor of 1.18 for each six-month period with TSH suppression).
  • Increased insulin sensitivity (in diabetics, this decreases the daily insulin requirement!).

Prognostic factors

  • In patients requiring hemodialysis, hypothyroidism, as well as TSH levels in the upper normal range, is associated with increased mortality (death rate) (HR 1.47, 95% confidence interval 1.34-1.61; p < 0.001).