Calcium deficiency tetany

Calcium channel Ca channel), 789-790,177 Calcium deficiency tetany, 801... 

The site and type of bone deformity seen in rickets depend on the age of the child. In a small infant, deformities of the forearms and anterior bowing of the distal tibias are more common. Clinical features such as craniotabes (areas of thinning and softening in the bones of the skull), hypotonia, and tetany are common in vitamin D-deficiency rickets, which occurs more frequently in infants 1 year old or younger. These features may be absent in calcium-deficiency rickets, which usually presents after the age of 1 year or after the child has been... 

Calcium deficiency is manifested by tetany with characteristic carpopedal spasm and, at times, laryngospasm and convulsive seizures. When tetany is present, the concentration of serum calcium is usually less than 8 mg. per 100 ml. Tetany occurs in osteomalacia and often accompanies rickets, sprue, the celiac syndrome, and other steatorrheas. 

Calcium and magnesium deficiency also occur in some patients with the malabsorption syndrome and this may lead to tetany or bone changes. Low blood calcium levels may result from decreased absorption associated with lack of effective compensatory parathyroid activity. In patients in whom secondary hyperparathyroidism is effective, extensive loss of calcium from the bones may occur. The cause of the defective absorption of calcium in patients of the sprue group is complex and not yet fully understood (B3, Dl, Jl, M7, Nl). It is important that complications such as calcium or magnesium deficiency should be corrected before the final steps of definitive diagnosis are attempted. If this is not done, the secondary effects may obscure the results of other tests. 

Hypocalcemia - To correct plasma calcium levels (eg, neonatal tetany and tetany due to parathyroid deficiency, vitamin D deficiency, alkalosis) prevention of hypocalcemia during exchange transfusions conditions associated with intestinal malabsorption. 

Hypomagnesemia - Magnesium sulfate is used as replacement therapy in magnesium deficiency especially in acute hypomagnesemia accompanied by signs of tetany similar to those observed in hypocalcemia. In such cases, the serum magnesium (Mg++) level is usually below the lower limit of normal (1.5 to 2.5 or 3 mEq/L) and the serum calcium (Ca++) level is normal (4.3 to 5.3 mEq/L) or elevated. 

Fracture In Paget patients, treatment regimens of etidronate exceeding the recommended daily maximum dose of 20 mg/kg or continuous administration for periods greater than 6 months may be associated with an increased risk of fracture. Hypocalcemia Hypocalcemia has occurred with pamidronate therapy. Rare cases of symptomatic hypocalcemia (including tetany) occurred during pamidronate treatment. If hypocalcemia occurs, consider short-term calcium therapy. Hypocalcemia must be corrected before therapy initiation with alendronate and risedronate. Also effectively treat other disturbances of mineral metabolism (eg, vitamin D deficiency). 

The main features of hypocalcemia are neuromuscular—tetany, paresthesias, laryngospasm, muscle cramps, and convulsions. The major causes of hypocalcemia in the adult are hypoparathyroidism, vitamin D deficiency, chronic kidney disease, and malabsorption. Neonatal hypocalcemia is a common disorder that usually resolves without therapy. The roles of PTH, vitamin D, and calcitonin in the neonatal syndrome are under active investigation. Large infusions of citrated blood can produce hypocalcemia by the formation of citrate-calcium complexes. Calcium and vitamin D (or its metabolites) form the mainstay of treatment of hypocalcemia. 

After the plasma Mg levels had decreased, plasma calcium levels began to drop. The drop in plasma Ca was moderate compared with that in Mg, Plasma Ca levels decreased even though the subjects were receiving adequate amounts of calcium and vitamin D. Neuromuscular symptoms developed after about 4 weeks of the diet. These symphims included tetany, lack of reflexes, tremors, and muscle lAreak-ness. Tetany may be mild, as in mouth twitches, or more severe, as in painful spasms. Hypocalcemia produces a tetany similar to that produced by Mg defi cicncy however. Mg deficiency induced tetany can occur with normal serum calcium levels. The tetany of Mg deficiency can be reversed by administration of Mg but not calcium. Tetany can result from low concentrations of Ca or Mg in the extracellular fluids which surround the nerves) or from an alkaline pH. Low potassium levels in the extracellular fluids, however, do not result in tetany. 

Calcium gluconate is indicated in hypocalcemia associated with neonatal tetany and tetany due to parathyroid difficulty, vitamin D deficiency, or alkalosis in prevention of tetany during exchange transfusions and in conditions related to malabsorption. 

Hypocalcemia can be caused by PTH deficiency, vitamin D deficiency, various pharmacological agents, and miscellaneous disorders (Table 35.5) (18). A state of hypocalcemia will inhibit calcitonin release. This results in an elevation of PTH biosynthesis and release and indirectly causes an increase in the production of vitamin D. The left wing of Arnaud s butterfly model (Fig. 35.1) would be activated to increase serum calcium concentrations. In the absence of calcitonin, osteoclast activity is unregulated therefore, bone resorption is accelerated. In acute cases of hypocalcemia, specifically in the case of hypocalcemic tetany, PTH is administered to correct the hormonal imbalance. 

Symptoms of hypocalcemia vary depending on the severity and duration of the deficiency, and in some cases, a patient even may be asymptomatic. If a patient is symptomatic, initial complaints may include numbness and/or tingling around the mouth or in the hands and feet muscles spasms in the feet, face, and hands that in more severe cases may expand to tetany (uncontrolled muscle contraction) seizures, bronchospasms accompanied by respiratory distress, and cardiac arrhythmias. Low levels of calcium in the bones may lead to disorders such as decreased bone minereralization referred to as rickets in children, osteomalacia in adults, or osteoporosis (a condition more prominent in postmenopausal women). 

Although the major part of the body s calcium is in bones, the most important functions of calcium are in the maintenance of muscle contractility and responses to hormones and neurotransmitters. To maintain these essential regulatory functions, bone calcium is mobilized in deficiency, so as to ensure that the plasma and intracellular concentrations are kept within a strictly controlled range. If the plasma concentration of calcium falls, neuromuscular regulation is lost, leading to tetany. 

TOXICITY. There Is no known phosphorus toxicity per se. However, excess phosphate consumption may cause hypocalcemia (a deficiency of calcium in the blood) and result in enhanced neuroexcitability, tetany, and convul-... 

Tetany—A deficiency of vitamin D may cause tetany, though it is not the only cause. Tetany may also result from insufficient absorption of calcium or from a disturbance of the parathyroid gland. Tetany is characterized by muscle twitching, cramps, convulsions, and low serum calcium—less than 7 mg per 100 ml. 

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