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The Kidney Connection - Secondary Hyperparathyroidism
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The parathyroids consist of four small pea-sized glands situated just behind the thyroid gland in the front part of the neck. Their purpose is to produce the parathyroid hormone which assists in the regulation of calcium and phosphorus in the body. Over time, too much phosphorus, and too little calcium and active vitamin D, can cause the gland to produce too much parathyroid hormone. When the body produces too much of this hormone, hyperparathyroidism occurs. When this happens in response to low blood calcium caused by another condition such as chronic kidney disease (CKD), it is known as secondary hyperparathyroidism (SHPT). CKD the Most Common Cause The most common cause of SHPT is CKD. SHPT occurs when damaged kidneys do not convert enough vitamin D to its active form or they may not excrete enough phosphorus. When this happens, insoluble (a substance that cannot be dissolved) calcium phosphate forms in the body and removes calcium from circulation. Either one of these processes leads to hypocalcemia (low blood calcium levels). It can also lead to hypertrophy (an abnormal increase in size) of the glands. And elevated serum phosphorus levels may contribute to such SHPT abnormalities as hypocalcemia. Complications of SHPT If SHPT is left untreated, it can progress to what is known as tertiary HPT. This happens when hypertrophy of the PT gland is irreversible. SHPT can contribute to too much calcium being drawn from the bones, leaving them brittle or weak and can cause pain.. Other complications of SHPT may include nerve and skin problems and itching. It can also contribute to vascular calcification (a buildup of calcium in the heart) and has been linked to higher cardiovascular hospitalizations and mortality in hemodialysis patients. Calcium can also build up in other areas of the body, such as in the tissues and on the skin, where it does not belong. Diagnosing and Treating SHPT Some experts believe that SPTH will eventually affect 30%-40% of stage 3 CKD patients, 50%-80% of stage 4 patients, and just about anyone on dialysis with stage 5 CKD. During the process of diagnosing SHPT, your doctor may order tests that show: - Abnormally high serum phosphorus and urine calcium levels;
- Elevated PTH, or parathormone, levels;
- Elevated serum alkaline phosphatase (an enzyme in the blood, liver, intestines, and bone cells);
- Varied vitamin D levels; and
- Bone problems, including low mineral density.
Among the treatments used for CKD patients with SHPT are vitamin D medications, calcium supplementation, and phosphate restriction. More Information For more information about the relationship about chronic kidney disease and secondary hyperparathyroidism, log onto the following websites:
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