Calciumspiegel

Calciumspiegel, in medical and scientific usage, denotes the concentration of calcium in the body’s extracellular fluids, most commonly assessed in blood serum or plasma. Clinically, it is reported as total serum calcium or as ionized (free) calcium. Because most of total calcium is bound to proteins such as albumin, variations in albumin can alter the total value without changing the physiologically active ionized fraction; thus ionized calcium or albumin-corrected calcium is often preferred when precise calcium status is needed.

Normal ranges vary by age and assay but are roughly:

- total calcium: about 2.15–2.55 mmol/L (8.6–10.2 mg/dL)

- ionized calcium: about 1.12–1.32 mmol/L (4.5–5.2 mg/dL)

Regulation is maintained by a hormonal system including parathyroid hormone (PTH), vitamin D, and calcitonin. PTH raises serum calcium by increasing bone resorption, enhancing renal calcium reabsorption, and promoting active vitamin D formation, which increases intestinal absorption. Calcitonin lowers calcium by inhibiting bone resorption. Kidney function, phosphate balance, acid–base status, and nutritional status influence calciumspiegel as well.

Clinical relevance: abnormal calciumspiegel signals disturbances in bone metabolism, kidney function, endocrine regulation, or malignancy. Hypercalcemia can cause fatigue, polyuria, nausea, and arrhythmias; common causes include primary hyperparathyroidism and malignancy-related phenomena such as PTH-related peptide. Hypocalcemia may present with tingling, muscle cramps, or seizures and arises from hypoparathyroidism, vitamin D deficiency, chronic kidney disease, or severe illness. Management focuses on treating the underlying cause and correcting calcium balance as appropriate.