Compared with karyotyping, FISH is much more sensitive and specific in determining several abnormalities (except for point mutations) but is limited by the currently available gene probes. Fluorescence in situ hybridization utilizes fluorescent probes to identify and locate specific genes on chromosomes. However, chromosomal microarray analysis is not useful in identifying certain variations such as balanced translocations. Chromosomal microarray analysis is a comparative technique that utilizes fluorescence to identify and quantify specific genetic sequences and is much more sensitive in identifying copy number variants, such as microdeletions or microduplications. Karyotyping is not sensitive in identifying small abnormalities and is a labor-intensive process. Karyotyping is the staining, organization, and visualization of chromosomes, which can help identify aneuploidy and major structural changes. Lowers Ca ++ by 1 to 3 mg per dL (0.25 to 0.Chromosomal testing can be accomplished using several techniques, all of which can identify chromosomal abnormalities. May exacerbate heart failure in elderly patients Severe↑Ca ++ > 14 mg per dL (3.5 mmol per L) Normal saline 2 to 4 L IV daily for 1 to 3 daysĮnhances filtration and excretion of Ca ++ Immobilization, with high bone turnover (e.g., Paget's disease, bedridden child) Vitamin A intoxication (including analogs used to treat acne)įamilial hypocalciuric hypercalcemia: mutated calcium-sensing receptor Milk-alkali syndrome (from calcium antacids) Local osteolysis* (mediated by cytokines) multiple myeloma, breast cancer Solid tumors, especially lung, head, and neck squamous cancers, renal cell tumors
Humoral hypercalcemia of malignancy* (mediated by PTHrP) Granulomatous disease sarcoidosis, berylliosis, tuberculosis Usually 25-hydroxyvitamin D 2 in over-the-counter supplements Sporadic, familial, associated with multiple endocrine neoplasia I or IIĪssociated with chronic renal failure or vitamin D deficiency
Aggressive intravenous rehydration is the mainstay of management in severe hypercalcemia, and antiresorptive agents, such as calcitonin and bisphosphonates, frequently can alleviate the clinical manifestations of hypercalcemic disorders. Hypercalcemic crisis is a life-threatening emergency. Many patients with primary hyperparathyroidism have a benign course and do not need surgery.
It is essential to exclude other causes before considering parathyroid surgery, and patients should be referred for parathyroidectomy only if they meet certain criteria. Parathyroid hormone is suppressed in malignancy-associated hypercalcemia and elevated in primary hyperparathyroidism. An initial diagnostic work-up should include measurement of intact parathyroid hormone, and any medications that are likely to be causative should be discontinued. Some other important causes of hypercalcemia are medications and familial hypocalciuric hypercalcemia. The most common causes of hypercalcemia are primary hyper-parathyroidism and malignancy. Clinical manifestations affect the neuromuscular, gastrointestinal, renal, skeletal, and cardiovascular systems. The diagnosis often is made incidentally in asymptomatic patients. Hypercalcemia is a disorder commonly encountered by primary care physicians.
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