McKenna's Pharmacology for Nursing, 2e

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P A R T 6  Drugs acting on the endocrine system

Iodine Solutions sodium iodide 131 I strong iodine solution, potassium iodide PARATHYROID AGENTS Antihypocalcaemic agents calcitriol teriparatide

Calcitonins calcimimetic calcitonin salmon (salcitonin) cinacalcet

THYROID AGENTS Thyroid hormones liothyronine thyroxine Antithyroid agents Thioamides carbimazole propylthiouracil

Antihypercalcaemic agents Bisphosphonates alendronate

clodronate etidronate ibandronate pamidronate risedronate tiludronate zoledronic acid

T his chapter reviews drugs that are used to affect the function of the thyroid and parathyroid glands. These two glands are closely situated in the middle of the neck and share a common goal of calcium homeostasis. Serum calcium levels need to be maintained within a narrow range to promote effective blood coagulation, as well as nerve and muscle function. In most respects, however, these glands are very different in structure and function.

Its name comes from the Greek words thyros (shield) and eidos (gland). It produces two hormones—thyroid hormone and calcitonin. Structure and function The thyroid is a vascular gland with two lobes—one on each side of the trachea—and a small isthmus connect- ing the lobes. The gland is made up of cells arranged in circular follicles . The centre of each follicle is composed of colloid tissue, in which the thyroid hormones produced by the gland are stored. Cells found around the follicle of the thyroid gland are called parafollicu- lar cells (see Figure 37.1). These cells produce another hormone, calcitonin , which affects calcium levels and

THE THYROID GLAND The thyroid gland is located in the middle of the neck, where it surrounds the trachea like a shield (Figure 37.1).

Thyroid cells

Parafollicular cells

Thyroid follicles

Colloid

Thioamides, iodines work here

Blood vessel

Thyroid replacement hormone replaces hormones from colloid when levels are low

Thyroid gland

Trachea

Parathyroid glands

FIGURE 37.1  The thyroid and parathyroid glands. The basic unit of the thyroid gland is the follicle.