Calcium and phosphorus

"It is essential to monitor calcium and phosphorus levels in people over 70 years of age to prevent osteoporosis."


Calcium and phosphorus are two of the most abundant mineral elements in the human body.

They are found mainly in the form of the mineral skeleton, in the form of a compound called hydroxyapatite.

  • Calcium has some very important functions such as, among others, its participation in muscle contraction, nervous excitability, blood coagulation or in the secretion of exocrine glands.
  • Phosphorus has important metabolic functions, participating in the regulation of enzymes and energy storage.
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When are calcium and phosphorus tests indicated?

Desde que nacemos y durante el crecimiento aumentan los depósitos de calcio.

Alrededor de los 30 años, se alcanza el valor máximo de masa ósea y, a partir de los 50 años, esa masa ósea comienza a disminuir.

Una dieta equilibrada consigue aportar la cantidad precisa de estos minerales.

Solamente en el caso de que exista algún problema en su absorción o eliminación, será necesario tomar suplementos.

Most frequent indications of this test:

  • Hyperparathyroidism.
  • Hypoparathyroidism.
  • Acute renal failure.
  • Chronic renal insufficiency.
  • Osteoporosis.
  • Rickets.

Do you have any of these diseases?

You may need to have a calcium and phosphorus test

Analysis of calcium and phosphorus, what do they mean?

Due to these important functions, serum calcium levels are maintained at very low levels (between 8 and 10.5 mg/dl.) and the maintenance of calcium and phosphorus balance is carried out by three main hormones, parathyroid hormone (PTH), vitamin D and calcitonin, which act at the level of three organs: bone, kidney and intestine.

Paratohormone (PTH) responds to low levels of calcium by promoting tubular reabsorption of calcium in the kidney, elimination of phosphorus in the urine and also the synthesis of the active form of vitamin D (1,25- dihydroxycholecalciferol). In the bone, parathyroid promotes bone resorption, thus releasing calcium and phosphate into the bloodstream.

Vitamin D promotes the absorption of intestinal calcium and phosphorus. It also favors the intestinal absorption of calcium, an acidic medium and the presence of proteins, while phytic acid, present in some cereals, fatty acids or oxalate, decreases their absorption.

Calcitonin also regulates calcium levels since it is secreted when calcium levels are high and favors its deposit in the bone by decreasing bone resorption.

Most of the phosphorus is found along with calcium forming the bone.

Normal serum phosphate levels in adults range from 2.5 to 4.5 mg/dl, while children, because of their growth status, have slightly higher phosphate levels, between 4 and 7 mg/dl.

It is important to perform the extraction on an empty stomach, since the serum phosphate values decrease after meals.

To measure phosphate in urine, it is necessary to collect it during 24 hours, due to the wide diurnal variation in phosphate elimination.

There are numerous pathologies in which the phospho-calcium metabolism is altered and which can lead to hyper- or hypocalcemia. Among the causes of increased serum calcium may be hyperparathyroidism or tumors. Causes of hypocalcemia may include hypoparathyroidism or kidney failure.

Where do we do it?


The Clinical Biochemistry Service
of the Clínica Universidad de Navarra

The Clinical Biochemistry Service of the Clinica Universidad de Navarra is responsible for performing the biochemical analyses requested by the medical specialists of our center.

We carry out technical quality controls to guarantee the proper functioning of the equipment and the highest precision in the results obtained from the samples.

In order to guarantee excellence in patient service, we offer the response with the results of the analyses in the shortest possible time, responding in only 46 minutes in some cases of general analysis.

Organized in care units

  • General biochemistry.
  • Electrolytes.
  • Hormones, urine and proteins.
  • Markers.
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Why at the Clinica?

  • Maximum speed in offering the analytical results.
  • We carry out quality controls to guarantee the correct and most precise results obtained.
  • We work in a multidisciplinary way with all the departments of the Clinic.