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Calcium, Total

Plasma calcium exists in the blood in three forms; 50% is ionized, 40-45% is protein bound, and 5-10% is complexed to anions such as bicarbonate, citrate, sulfate, phosphate, and lactate. Plasma ionized calcium is the biologically active moiety. Total calcium levels are maintained between 8.8 and 10.2 mg/dL. Parathyroid hormone and levitra online shop vitamin D regulate normal plasma calcium levels by their actions on kidney, intestine, and bone ion transport.

The main causes of hypercalcemia are primary hyperparathyroidism, malignant disease, and chronic renal failure. The differential diagnosis of hypercalcemia depends on the clinical setting. Overall, primary hyperparathyroidism and malignancy account for 80 – 90% of hypercalcemia cases. However, primary hyperparathyroidism is canada levitra generic the cause of ~60% of ambulatory cases and of ~25% of inpatient cases, whereas malignancy causes ~35% of ambulatory cases and 65% of inpatient cases.

Malignancies can raise serum calcium levels by either direct bone destruction or secretion of calcemic factors. Patients with squamous cell carcinoma of cheapest generic price viagra the lung, metastatic breast cancer, multiple myeloma, and renal cell carcinoma are most prone to buy cheapest levitra hypercalcemia. These tumors may produce PTH related protein (PTH-rp) which binds to PTH receptors, but is not detected by standard intact PTH immunoassays. Specific assays for PTH-rp are available.

The prevalence of hyperparathyroidism in the general population is 1 to 2 cases per 1000 people, but is more frequent in the elderly and in women. The most common pathological lesion is a single parathyroid adenoma (85% of cases) or chief cell hyperplasia (10%). Parathyroid carcinoma occurs in 1 to 3% of cases. Hyperparathyroidism also occurs in multiple endocrine neoplasia type 1 and 2A. Patients identified by laboratory screening are commonly asymptomatic. Presentation with kidney stones is unusual today, but 5% of patients with kidney stone disease have primary hyperparathyroidism. Finding an elevated PTH level in a patient with hypercalcemia makes the cialis soft tablets diagnosis.

The signs and symptoms of hypercalcemia are summarized in the following table.

Mental

Neurological & Skeletal

GI & Urological

Fatigue

Reduced muscle tone

Nausea

Obtundation

Muscle weakness

Vomiting

Apathy

Myalgia

Polyuria

Lethargy

Pain

Polydipsia

Confusion

Deep tendon reflexes

Dehydration

Disorientation

Anorexia

Coma

Constipation

Evaluation of hypercalcemia usually begins with measurement of viagra delivered on saturday by fedex total calcium. If total calcium is markedly elevated, an ionized calcium level is usually not needed. Slightly to moderately elevated total calcium should be confirmed by measurement of ionized calcium. The patient’s history may indicate the cause, such as; immobilization for more than a week, drug therapy, hyperthyroidism, adrenal insufficiency, or familial hypocalciuric hypercalcemia. If time permits, total calcium levels should be repeated two more times to rule out a transient cause of hypercalcemia before undertaking a complete work-up. If hypercalcemia is still evident, serum albumin and total protein should be determined. Calcium levels should be corrected for elevated albumin levels (see below). If total protein is levitra 100 high, but albumin is normal or low, a monoclonal gammopathy should be ruled out by serum protein electrophoresis. Serum chloride, phosphorus and intact PTH are also useful in diagnosing the most frequent causes of hypercalcemia; malignancy and purchase female viagra hyperparathyroidism. Serum chloride is mildly elevated in primary hyperparathyroidism.

Test

Hyperparathyroidism

Malignancy

Total calcium (mg/dL)

<12.4

>12.4

Chloride(meq/L)

>103

<103

Phosphorus

normal to low

normal

Chloride : phosphorus ratio

29 or greater

<29

Intact PTH

elevated

suppressed

PTH-rp

normal

elevated

Calcitriol

elevated

low

Hypocalcemia most commonly results from PTH deficiency or failure to produce 1,25 dihydroxy vitamin D. The most common causes of hypoparathyroidism are parathyroid or thyroid surgery and parathyroid infiltration by cancer, sarcoid, amyloid or hemochromatosis. Acute illnesses such as pancreatitis, hepatic failure, sepsis, and various medications can also cause hypocalcemia. The normal response to a fall in the plasma ionized calcium level is increased PTH secretion and 1,25 dihyroxy vitamin D synthesis, leading to cialis for woman increased calcium absorption from the intestine and increased resorption from bone and kidneys.

Some drugs are associated with hypocalcemia. Gentamicin and cisplatin cause renal magnesium loss, which leads to hypocalcemia. Heparin therapy releases fatty acids that bind calcium ions and cause transient hypocalcemia. Anticonvulsants such as dilantin and wow it's great phenobarbital induce the microsomal oxidase pathway which accelerates inactivation of vitamin D. Loop diuretics such as furosemide enhance renal calcium excretion. Phosphate salts bind up calcium ions causing hypocalcemia.

The laboratory evaluation of a low total plasma calcium level should include measurement of ionized calcium, magnesium, and phosphorus levels. Low ionized calcium rules out artefactual causes of hypocalcemia, such as hypoalbuminemia. Abnormally high or low magnesium levels should be excluded because they can inhibit PTH secretion. A low serum phosphorus level is consistent with vitamin D deficiency, while a high level suggests chronic renal failure or pseudohypoparathyroidism. Measurement of intact PTH levels helps to differentiate between conditions caused by PTH and vitamin D defects. The demonstration of an inappropriately low intact PTH level in the presence of hypocalcemia is consistent with the diagnosis of hypoparathyroidism. Serum 25-hydroxyvitamin D levels can be measured to confirm vitamin D deficiency.

Total calcium levels are effected by changes in plasma protein concentrations. Most of the protein bound fraction of calcium is bound to albumin; each 1 g/dL of albumin binds 0.8 mg/dL of calcium. Three formulas have been used to correct calcium for decreased serum albumin levels:

%Calcium bound = 8 (albumin) + 2(globulin) + 3

Corrected calcium = measured Calcium /0.6 + [total protein/8.5]

Corrected calcium = Calcium – albumin + 4

Each formula will give a slightly different value for corrected calcium. A better approach is to directly measure ionized calcium levels.

Two of the four approved gadolinium based magnetic resonance (MR) imaging contrast agents, gadodiamide (Omniscan) and gadoversetamide (OptiMARK), have recently been shown to http://www.finquesbalada.com/herbal-alternative-to-cialis interfere with calcium measurements on some chemistry analyzers, resulting in falsely low values. Patients with normal renal function may have spuriously low calcium measurements up to 24 hours after administration of these contrast agents, but patients with renal insufficiency may be affected for up to 4.5 days. However, the Vitros chemistry analyzers used throughout the Saint Luke’s Health System are not adversely affected (Am J Clin Pathol 2004;121:282-92).

Reference range is 8.8 - 10.2 mg/dL. Calcium levels less than 6.0 mg/dL or greater than 13.0 mg/dL are considered critical values.

Specimen requirement is one SST tube or one green top (heparin) tube of prices levitra blood. Prolonged venous stasis should be avoided because it can produce artefactual hypercalcemia.

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