and J. Carl Pallais1
(1)
Harvard Medical School Division of Endocrinology, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
Abstract
Cardiovascular symptoms are often the first signs and symptoms of underlying endocrinopathies. This chapter reviews endocrine disorders with a focus on cardiovascular changes and presentations.
Abbreviations
ACTH
Adrenocorticotropic hormone
AF
Atrial fibrillation
AI
Adrenal insufficiency
AIT
Amiodarone-induced thyrotoxicosis
BMD
Bone mineral density
CAD
Coronary artery disease
CHF
Congestive heart failure
CMV
Cytomegalovirus
CO
Cardiac output
CV
Cardiovascular
CVD
Cardiovascular disease
DBP
Diastolic blood pressure
DTR
Deep tendon reflexes
EKG
Electrocardiogram
GH
Growth hormone
HIV
Human immunodeficiency virus
HR
Heart rate
HTN
Hypertension
IGF-1
Insulin-like growth factor – 1
IV
Intravenous
LV
Left ventricular
OGTT
Oral glucose tolerance test
PAC
Plasma aldosterone concentration
PE
Physical exam
PRA
Plasma renin activity
PTH
Parathyroid hormone
PTU
Propylthiouracil
PVR
Peripheral vascular resistance
RAI
Radioactive iodine
RAIU
Radioactive iodine uptake
SBP
Systolic blood pressure
SSKI
Supersaturated potassium iodide
SV
Stroke volume
SVR
Systemic vascular resistance
T3
Triiodothyronine
T4
Thyroxine
TB
Tuberculosis
TFT
Thyroid function tests
TSH
Thyroid stimulating hormone
TTE
Trans-thoracic echocardiography
WNL
Within normal limits
Introduction
Cardiovascular symptoms are often the first signs and symptoms of underlying endocrinopathies. This chapter reviews endocrine disorders with a focus on cardiovascular changes and presentations.
Thyroid (Table 32-1)
Table 32-1
Cardiovascular changes with thyroid disease
CV parameter | Hyperthyroid | Hypothyroid |
|---|---|---|
Systemic vascular resistance | Decreased | Increased |
Heart rate | Increased | Decreased |
Cardiac output | Increased | Decreased |
Blood volume | Increased | Decreased |
Hyperthyroidism/Thyrotoxicosis
Hyperthyroidism/Thyrotoxicosis – physiologic manifestations of excessive quantities of thyroid hormones (endogenous or exogenous) [1]
Signs/Symptoms:
General – weight loss, tremors, insomnia, heat intolerance, warm moist skin, hyperreflexia, hyperdefecation. Goiter may be present. Proptosis may occur in Graves’ disease.
Cardiovascular (CV) – ↑ sympathetic tone (tachycardia, palpitations, atrial fibrillation [AF]), ↑ cardiac output [CO] (from ↑ heart rate [HR], in severe cases ↑ stroke volume [SV]), ↑ inotropy, ↑ circulatory demand from hypermetabolism, ↓ peripheral vascular resistance (PVR), ↑ pulse pressure
Physical exam (PE) findings: dynamic precordium, systolic ejection murmur, enhanced S1, Means-Lerman scratch (systolic pleuropericardial friction rub)
Arrhythmia: 2–20 % of patients will have AF. Cardioversion is not indicated when thyrotoxicosis is present. 60 % revert spontaneously within 4 months after normalization of thyroid function tests (TFT). Anticoagulation is recommended in patients with AF who are at moderate risk for stroke on the basis of identified risk factors [2]. Patients with newly diagnosed AF with clearly reversible hyperthyroidism and no risk factors for thromboembolism do not warrant long-term anticoagulation.
Laboratory testing:
↓ Thyroid stimulating hormone (TSH), ↑ thyroid hormones (free thyroxine [T4] and/or triiodothyronine [T3]); ↑ thyroid antibodies in Graves’ disease
Radioactive iodine uptake (RAIU)/thyroid scan – in the setting of a suppressed TSH, RAIU measures autonomous activity of the thyroid gland; thyroid scan measures the pattern of distribution of iodine trapping within the gland (homogeneous, heterogeneous, focal)
Causes:
↑ RAIU (thyroid scan pattern): Graves’ disease (homogeneous), toxic multinodular goiter (heterogeneous), toxic adenoma (focal), TSH-secreting pituitary tumors (homogenous)
↓ RAIU: Iodide-induced thyrotoxicosis, thyroiditis (autoimmune, post-viral/subacute, drug induced [amiodarone, lithium, interferon-alpha, interleukin-2, granulocyte macrophage colony-stimulating factor]), exogenous thyroid hormone ingestion, struma ovarii
Treatment:
β-blockers (preferably propranolol, atenolol, or metoprolol which also ↓ T4 to T3 conversion), methimazole, ± inorganic iodine (after methimazole) to ↓ release of preformed thyroid hormone (Wolff-Chaikoff effect), ± glucocorticoids (↓T4 to T3 conversion)
RAI ablation, thyroidectomy
Special Cases of Hyperthyroidism
1.
Thyroid Storm – accelerated hyperthyroidism. Precipitants usually infection, trauma, surgery [3].
Signs/Symptoms: Fever, sweating, marked tachycardia, arrhythmias, pulmonary edema, high-output congestive heart failure (CHF), tremulousness, delirium, psychosis, abdominal pain, jaundice. Can be fatal if not treated.
Treatment: Intensive care, propylthiouracil (PTU), super-saturated potassium iodide (SSKI) after PTU, dexamethasone. ±β-blocker depending on cardiac state
2.
Subclinical Hyperthyroidism – biochemical findings of low TSH with normal T4 and T3 levels
Increased risk for AF if TSH <0.1 mU/L (2 × ↑ risk over 10 years), and ± ↓ bone mineral density (BMD) [4]
Treatment impacts hemodynamic parameters (↓HR, ↓CO, ↑systemic vascular resistance [SVR], ↓ premature atrial or ventricular contractions, ↓ left ventricular [LV] mass) and improve BMD, especially in older adults [5]
Assessment of cause and appropriate treatment recommended for elderly, postmenopausal osteoporosis, cardiac disease (left atrial enlargement, AF, CHF, angina), and infertility
Hypothyroidism
Signs/Symptoms: Dry/coarse skin, peri-orbital puffiness, delayed relaxation phase of deep tendon reflexes (DTR), hair loss, fatigue, weight gain [6, 7]
CV Signs/Symptoms: ↓ CO (↓ SV & ↓HR), ↑ PVR at rest with possible diastolic hypertension (HTN), narrow pulse pressure, ↓ blood volume, ↓ circulation → coolness, pallor; pericardial effusion
Labs: ± ↑CK and LDH (skeletal muscle source), ↑ LDL
Electrocardiogram (EKG) changes: sinus bradycardia, prolonged PR, low voltage, non-specific ST-segment changes, flattened/inverted T-waves
Trans-thoracic echocardiogram (TTE): resting LV diastolic dysfunction
Diagnosis: Primary hypothyroidism = ↑ TSH, ↓ T4 & T3. Central hypothyroidism = low/normal TSH, ↓ T4 & T3.
Causes: Primary hypothyroidism is much more common than central hypothyroidism
Primary hypothyroidism – Hashimoto’s thyroiditis, infiltrative disease (sarcoid, hemochromatosis, etc.), thyroid resection, post-radioiodine therapy, iodine deficiency, drugs (lithium, thionamides, sulfonamides, iodine, tyrosine kinase inhibitors)
Thyroiditis (painless/subacute/postpartum) can cause transient hyperthyroidism followed by transient hypothyroidism
Central hypothyroidism – pituitary tumor, pituitary surgery, radiation therapy
Treatment: Thyroid hormone replacement; start at low replacement dose and slowly titrate up if coronary artery disease (CAD) suspected (thyroid hormone replacement may exacerbate angina)
Note: Hypothyroidism decreases the metabolism of many cardiac drugs. Care must be exercised when treating cardiovascular disease (CVD) in hypothyroid patients or initiating thyroid hormone replacement in these patients.
Special Cases of Hypothyroidism
1.
Myxedema coma – condition seen with severe long-standing hypothyroidism, primarily in older patients. High mortality rate [8]
Signs/Symptoms: Comatose state, hypothermia, bradycardia, hypotension, delayed DTR/areflexia, seizures, hypoventilation, hyponatremia, hypoglycemia
Risk factors: Age, exposure to cold, infection, trauma, central nervous system depressants, anesthetics
Diagnosis: Clinical diagnosis, delay of treatment worsens prognosis. Treatment should be initiated while awaiting thyroid function test results.
Treatment: Intravenous (IV) levothyroxine 500 mcg load, 100 mcg IV daily, hydrocortisone 100 mg IV q8h to cover for relative adrenal insufficiency; correction of metabolic derangements (hyponatremia, hypoglycemia), as well as respiratory failure (mechanical ventilation), and work-up for coexisting disease
2.
Euthyroid Sick Syndrome (Non-Thyroidal Illness Syndrome) – Abnormalities of circulating TSH, T4, and T3 levels without underlying thyroid disease. Occurs in fasting and illness [9] (Table 32-2)
Table 32-2
Stages of euthyroid sick syndrome
Stage | Severity of illness | T3 or free T3 | T4 or free T4 | Reverse T3 | TSH |
|---|---|---|---|---|---|
Stage 1 | Mild (ex. URI) | ↓ | Normal < div class='tao-gold-member'>
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