Epidemiology
Etiology
Physiology
- Myxedema + Obesity: central hypoventilation with respiratory muscle weakness leads to hypoxia and acidosis (with resultant pulmonary vasoconstriction)
- Ventilatory Drive in Response to Hypoxia and Hypercapnia: decreased (corrects with treatment)
Clinical Manifestations
Endocrinologic Manifestations
- Goiter (see Goiter, [[Goiter]])
- May occur substernally
- Best detected by I131 scan
- Hyperhomocysteinemia (see Hyperhomocysteinemia, [[Hyperhomocysteinemia]])
Neuro Manifestations
- Fatigue
- Hyporeflexia: correlates with propensity for respiratory failure
Pulmonary Manifestations
- Physiology: probably due to transcapillary filtration of liquid and protein
- Diagnosis
- Pleural Fluid: transudate, when effusion occurs at the same time as pericardial effusion
- Isolated pleural effusions can be either transudate or exudate
- Clinical
- Most cases of hypothyroidism-associated pleural effusion have a coexistent pericardial effusion (52% with pericardial effusion had a pleural effusion also)
Pulmonary Hypertension (see Pulmonary Hypertension, [[Pulmonary Hypertension]])
- Epidemiology: both hypothyroidism and hyperthyroidism have been found to be associated with pulmonary hypertension
- In an echocardiographic study, more than 40% of patients with thyroid diseases had pulmonary hypertension
- One case of biopsy-proven pulmonary veno-occlusive disease was reported in a patient with Hashimoto thyroiditis
- Study of adult patients with pulmonary hypertension reported a 49% prevalence of autoimmune thyroid disease (both hypothyroidism and hyperthyroidism): possible common immunogenetic susceptibility
- Physiology: likely due to hypoventilation (with associated with altered CNS respiratory drive, partial neuropathic component, and partial myopathic components)
Obstructive Sleep Apnea (OSA) (see Obstructive Sleep Apnea, [[Obstructive Sleep Apnea]])
- OSA (may respond to thyroid hormone replacement alone in some cases): hypothyroidism may induce mucopolysaccharide and protein extravasation in the face, predisposing upper airway obstruction
Acute/Chronic Hypoventilation (see Acute Hypoventilation, [[Acute Hypoventilation]] and Chronic Hypoventilation, [[Chronic Hypoventilation]])
- Diagnosis
- ABG: usually normal with hypothyroidism alone
- Hypothyroidism + Obesity: moderate hypoxemia with hypercapnia
- PFT’s: usually normal in presence of hypothyroidism alone
- Hypothyroidism + Obesity: VC, TLC, RV, IC, and ERV may be decreased
- MIP+MEP: inspiratory and expiratory muscle weakness
- Clinical: may manifest as failure to wean from ventilator
Cardiac Manifestations
Pericardial Effusion (see Pericardial Effusion, [[Pericardial Effusion]])
- Epidemiology
- Diagnosis
- Pericardiocentesis: protein content ranges from 22-76 g/L
- Clinical
- Treatment
Hematologic Manifestations
- Anemia (see Anemia, [[Anemia]])
Treatment
- Thyroid Hormone Replacement
- Pleural effusion resolves with treatment
- Corrects PFT and ventilation abnormalities
- Enhances type 2 pneumocyte maturation and surfactant production in “in vitro” and animal studies
- Intra-amniotic administration decreases incidence of infant respiratory distress syndrome in premature infants
References
- Pulmonary hypertension and thyroid disease. Chest 2007;132:793–7
- Pulmonary arterial hypertension and thyroid disease. Chest 2001;119:1980–1
- Cardiovascular abnormalities in hyperthyroidism: a prospective Doppler echocardiographic study. Am J Med 2005;118:126–31
- Pulmonary veno-occlusive disease in a patient with a history of Hashimoto’s thyroiditis. Indian J Chest Dis Allied Sci 2005;47:289–92
- High prevalence of autoimmune thyroid disease in pulmonary arterial hypertension. Chest 2002;122:1668-73