Children need calcium to build bone tissue, but too much calcium can be harmful. Excess blood calcium, or hypercalcemia, causes the kidneys to work extra hard to remove the overload. Such high levels lead to the formation of kidney stones. Diet alone is not always the culprit of high calcium levels. Sometimes, high body calcium is caused by genetics, cancer or diseases.
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Calcium is an important mineral that the human body needs to build healthy bones, form blood clots, contract muscles and help nerves send messages. It is only available in nature and cannot be created by the body. Vitamin D assists in calcium absorption. Food is the best source of calcium, but calcium supplementation offers an alternative. The amount of calcium needed by the body increases as a child grows. Children 1 to 3 years of age need 500 mg per day, while 9 to 18 year olds need 1,300 mg. Excessive supplementation increases the chance of health problems in children.
Calcium supplements contain variable amounts of elemental calcium within calcium carbonate or calcium citrate. Foods supplemented with other calcium forms contain gluconate, lactate and phosphate. Fortified juices contain calcium citrate malate. The amount of calcium absorbed by the body depends on the amount of elemental calcium consumed. Hypercalcemia rarely results from dietary or supplemental calcium but tolerable levels should be measured in elemental calcium.
Relationship to Hormones
The primary regulators of blood calcium are parathyroid hormone and calcitonin. As blood calcium levels decrease, the parathyroid glands produce more parathyroid hormone. The parathyroid hormone stimulates bones to release calcium, and the digestive tract to absorb more calcium. As the levels of calcium rise, the thyroid gland produces calcitonin, which counteracts the calcium release and absorption. The primary cause of high calcium levels in children is hyperparathyroidism, or an overactive parathyroid gland. Also, certain medications, such as lithium and diuretics, may increase the release of parathyroid hormone.
Cancer and Other Diseases
Some cancerous tumors produce proteins that mimic parathyroid hormone, thus stimulating calcium release. Also, cancer within bone tissue may cause increased calcium release. Inflammatory diseases that raise levels of vitamin D in blood can stimulate excess calcium absorption and a genetically inherited disease called hypocalciuric hypercalcemia causes increased blood calcium from faulty calcium receptors. Secondary effects of diseases causing immobility increase bone calcium release because of the lack of weight-bearing exercise.
Untreated hypercalcemia causes various body system complications. Bones releasing excess calcium becomes thinner and prone to fractures. Growing children with hypercalcemia may develop spinal curvature and short stature. Calcium crystals may accumulate in kidneys and cause kidney stones. Excessive calcium damages the kidneys' ability to filter blood properly, resulting in renal disease. Even the nervous and cardiac systems are affected when showing signs of dementia, confusion and irregular heartbeats.
The first treatment option is hydration. Increasing the fluid flow through the kidneys will dilute blood calcium, making it less likely to damage the kidneys. Treatment with diuretics functions in the same way, by increasing fluid flow through the kidneys. Bisphosphate drugs will inhibit bone breakdown and adding calcitonin reduces calcium absorption. Treating high levels of vitamin D with glucocorticoids decreases calcium absorption as well. If kidneys are impaired, hemodialysis will remove excess toxins and calcium from the blood. Once blood calcium levels return to normal, underlying causes must be investigated.