The result of this age-related decrease in calcium absorption and adaptability is an increased need for calcium. In addition to estrogen's direct effect on bone metabolic processes, this hormone enhances calcium absorption and improves renal calcium conservation. A single cup of brewed coffee causes a deterioration in calcium balance by only 2 mg to 3mg, mainly by reducing calcium absorption. The amount of alcohol necessary to reduce calcium status is unknown. Diseases of the small intestine, liver, and pancreas can reduce calcium absorption.
Idiopathic hypercalciuria is characterized by excessive excretion of calcium in the urine.
Other diseases including hypoparathyroidism, diabetes, and thyrotoxicosis influence calcium absorption and retention by their effect on vitamin D metabolism. Some surgical procedures, particularly those involving the small and large intestine, may adversely affect calcium absorption.