Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

FRAG
9064
OSCAL
80579
Osmotic Fragility, Erythrocytes
Clinical Information: Spherocytes are osmotically fragile cells that rupture more easily in a
hypotonic solution than do normal RBCs. Because they have a low surface area: volume ratio, they lyse
at a higher osmolarity than do normal discocyte RBCs. Cells that have a larger surface area: volume
ratio, such as target cells or hypochromic cells are more resistant to lysing. After incubation, an increase
in hemolysis is seen in hereditary spherocytosis.
Useful For: Suspected hereditary spherocytic hemolytic anemia Confirming or detecting mild
spherocytosis
Interpretation: Increased lysis in 3 or more concentrations of sodium chloride indicates increased
red cell fragility.
Reference Values:
0.50 g/dL NaCl (unincubated)
Males: 0.0-47.8% hemolysis
Females: 0.0-31.1% hemolysis
0.60 g/dL NaCl (incubated)
Males: 18.7-67.4% hemolysis
Females: 10.9-65.5% hemolysis
0.65 g/dL NaCl (incubated)
Males: 4.4-36.6% hemolysis
Females: 0.2-39.3% hemolysis
0.75 g/dL NaCl (incubated)
Males: 0.8-9.1% hemolysis
Females: 0.0-10.9% hemolysis
Clinical References: Palek J, Jarolin P: Hereditary spherocytosis. In Hematology. 4th edition.
Edited by WJ Williams, E Beutler, AJ Erslev, MA Lichtman. New York, McGraw-Hill Book Company,
1990, pp 558-569
Osteocalcin, Serum
Clinical Information: Osteocalcin, the most important noncollagen protein in bone matrix,
accounts for approximately 1% of the total protein in human bone. It is a 49-amino acid protein with a
molecular weight of approximately 5800 daltons. Osteocalcin contains up to 3 gamma-carboxyglutamic
acid residues as a result of posttranslational, vitamin K-dependent enzymatic carboxylation. Its
production is dependent upon vitamin K and is stimulated by 1,25 dihydroxy vitamin D. Osteocalcin is
produced by osteoblasts and is widely accepted as a marker of bone osteoblastic activity. Osteocalcin,
incorporated into the bone matrix, is released into the circulation from the matrix during bone resorption
and, hence, is considered a marker of bone turnover, rather than a specific marker of bone formation.
Osteocalcin levels are increased in metabolic bone diseases with increased bone or osteoid formation
including osteoporosis, osteomalacia, rickets, hyperparathyroidism, renal osteodystrophy,
thyrotoxicosis, and in individuals with fractures, acromegaly, and bone metastasis. By means of
osteocalcin measurements, it is possible to monitor therapy with antiresorptive agents (bisphosphonates
or hormone replacement therapy [HRT]) in, for example, patients with osteoporosis or
hyper-calcemia.(1) Decrease in osteocalcin is also observed in some disorders (eg, hypoparathyroidism,
hypothyroidism, and growth hormone deficiency). Immunochemical and chromatographic studies have
demonstrated considerable heterogeneity for concentrations of circulating osteocalcin in normal
individuals and in patients with osteoporosis, chronic renal failure, and Pagetâ€s disease. Both intact
osteocalcin (amino acids 1-49) and the large N-terminal/midregion (N-MID) fragment (amino acids
1-43) are present in blood. Intact osteocalcin is unstable due to protease cleavage between amino acids
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