Endocrine Complications
Summary of Key Points
Introduction
• Endocrine dysfunction may occur as a direct result of cancer or may be a consequence of cancer therapy (e.g., surgery, radiation, chemotherapy, biological agents, and hormone therapy). Endocrine dysfunction may be an intentional consequence or an adverse effect of antineoplastic therapy.
• Hypopituitarism with clinically significant deficiencies of growth hormone, thyrotropin, gonadotropin, and corticotrophin may result from radiation (cranial or total body irradiation), surgery, or chemotherapy.
• Thyroid dysfunction from neck irradiation, immune therapy (interleukin-2), and small molecule tyrosine kinase inhibitors such as sunitinib may result in either hyperthyroidism or hypothyroidism.
• Gonadal dysfunction after surgery, radiotherapy, or chemotherapy results in disruption of puberty, infertility, and premature menopause.
• Adrenal dysfunction from agents such as ketoconazole or aminoglutethimide may result in glucocorticoid or mineralocorticoid deficiency.
• Pancreatitis and, occasionally, pancreatic exocrine or endocrine deficiencies may result from chemotherapy (l-asparaginase and streptozotocin).
Diagnostic Considerations
• A detailed history along with a complete physical examination is critical for diagnosis. Locations of primary and metastatic tumors along with past and current therapies are necessary elements of evaluation.
• Signs and symptoms such as delayed or precocious puberty, fatigue, weight loss or gain, amenorrhea, orthostatic hypotension, hyperpigmentation, or electrolyte abnormalities should prompt consideration of unrecognized endocrine dysfunction.
• When one hormonal deficiency is identified, others should be sought.
Evaluation and Treatment
Thyroid
• Primary hypothyroidism is characterized by a low free thyroxine (T4) level and an elevated thyroid-stimulating hormone (TSH) level, whereas central hypothyroidism is associated with a low free T4 level and inappropriately normal or low TSH levels. Replacement with levothyroxine is indicated and is highly effective.
