During menopause, estrogen levels are decreased, causing a multitude of side effects that include rapid bone loss. The lack of estrogen causes an increase in calcium release from bones, decreased calcium absorption by the gastrointestinal tract and increased urinary excretion of calcium. In most menopausal women, calcium levels remain normal or are decreased. More rarely, they may be increased by parathyroid gland dysfunction, certain cancers and excessive vitamin D supplement intake. Most people do not experience symptoms of hypercalcemia, and it is undetected until a routine blood test is performed. The symptoms that may be present include excessive thirst, frequent urination, constipation, muscle weakness and fatigue.
Hyperparathyroidism
The parathyroid glands secrete parathyroid hormone, which is the primary regulator of blood calcium levels. Primary hyperparathyroidism is caused by a defect in the parathyroid glands that leads to increased levels of parathyroid hormone, which increases blood calcium levels. A study in the August 2002 issue of the "World Journal of Surgery" reports that the incidence of primary hyperparathyroidism in postmenopausal women is 3.4 percent, and one-fifth of these women had elevated levels of blood calcium.
Cancers
MayoClinic.com reports that some cancers, especially lung and breast cancers, are associated with hypercalcemia. This is because these types of tumors secrete a protein that acts in similar fashion to parathyroid hormone. Additionally, bone cancer can increase the rate of bone breakdown and elevate calcium levels in the blood.
Vitamin D Supplements
The North American Menopause Society recommends a target calcium intake of 1,200mg per day and a daily intake of between 800 and 1000 international units of vitamin D. The Office of Dietary Supplements notes that, rarely, hypercalcemia is caused by dietary or supplemental calcium intake, but it may result from doses of vitamin D greater than 50,000 international units per day.
References
- "World Journal of Surgery"; Primary Hyperparathyroidism Revisited in Menopausal Women With Serum Calcium in the Upper Normal Range at Population-Based Screening Eight Years Ago; E. Lundgren et al.; August 2002
- Mayo Clinic: Hypercalcemia
- North American Menopause Society: Does Your Body Need More Calcium Around Menopause?
- Office of Dietary Supplements: Dietary Supplement Fact Sheet: Calcium
