Sorted By Test Name - Mayo Medical Laboratories

KITAS
88802
Interpretation: The interpretation of stone analysis results is complex, and beyond the scope of this
text. We refer you to chapter 25 of Smith LH: Diseases of the Kidney. Vol 1. Fourth edition. Edited by
RW Schrier, CW Gottscholk. Boston, MA, Little, Brown and Company, 1987. Calcium oxalate stones:
-Production of calcium oxalate stones consisting of oxalate dihydrate indicate that the stone is newly
formed and current urine constituents can be used to assess the importance of supersaturation. -Production
of calcium oxalate stones consisting of oxalate monohydrate indicate an old (>2 months since formed)
stone and current urine composition may not be meaningful. Magnesium ammonium phosphate stones
(struvite): -Production of magnesium ammonium phosphate stones (struvite) indicates that the cause of
stone formation was infection. -Treatment of the infection is the only way to inhibit further stone
formation. Ephedrine/guaifenesin stones: -Certain herbal and over-the-counter preparations (eg, Mah
Jung) contain high levels of ephedrine and guaifenesin. Excessive consumption of these products can lead
to the formation of ephedrine/guaifenesin stones.
Reference Values:
Quantitative report
Clinical References: 1. Lieske JC, Segura JW: Evaluation and medical management of kidney
stones. In Essential Urology: A Guide to Clinical Practice. Edited by JM Potts. Totowa, NJ, Humana
Press, 2004, pp 117-152 2. Lieske JC: Pathophysiology and evaluation of obstructive uropathy. In Smith's
Textbook of Endourology. Second edition. Edited by AD Smith, B Gopal Badlani, D Bagley, et al.
Hamilton, Ontario, Canada, BC Decker Inc., 2007, pp 101-106
KIT Asp816Val Mutation Analysis, Qualitative PCR
Clinical Information: Systemic mastocytosis is a hematopoietic neoplasm that can be included in the
general category of chronic myeloproliferative disorders (CMPDs). These neoplasms are characterized by
excessive proliferation of 1 or more myeloid lineages, with cells filling the bone marrow and populating
other hematopoietic sites. In systemic mastocytosis, mast cell proliferation is the defining feature,
although other myeloid lineages and B-cells are frequently part of the neoplastic clone. Function-altering
point mutations in KIT, a gene coding for a membrane receptor tyrosine kinase, have been found in
myeloid lineage cells in the majority of systemic mastocytosis cases. The most common KIT mutation is
an adenine-to thymine base substitution (A->T) at nucleotide position 2468, which results in an aspartic
acid-to-valine change in the protein (Asp816Val). Much less frequently, other mutations at this same
location are found and occasional cases with mutations at other locations have also been reported.
Mutations at the 816 codon are believed to alter the protein such that it is in a constitutively activated
state. The main downstream effect of KIT activation is cell proliferation. Detection of a mutation at the
816 codon is included as 1 of the minor diagnostic criteria for systemic mastocytosis in the World Health
Organization (WHO) classification system for hematopoietic neoplasms and is also of therapeutic
relevance, as it confers resistance to imatinib, a drug commonly used to treat CMPDs. It is now clear that
individual mast cell neoplasms are variable with respect to the number of cell lineages containing the
mutation; some having positivity only in mast cells and others having positivity in additional myeloid and
even lymphoid lineages. The mutation has not been reported in normal tissues.
Useful For: Diagnosing systemic mastocytosis
Interpretation: The test will be interpreted as positive or negative for KIT Asp816Val.
Reference Values:
An interpretive report will be provided indicating the mutation status as positive or negative.
Clinical References: 1. Garcia-Montero A, Jara-Acevedo M, Teodosio C, et al: KIT mutation in
mast cells and other bone marrow hematopoietic cell lineages in systemic mast cell disorders: a
prospective study of the Spanish Network on Mastocytosis (REMA) in a series of 113 patients. Blood
2006;108-2366-232 2. Valent P, Akin C, Sperr WR, et al: Diagnosis and treatment of systemic
mastocytosis: state of the art. Br J Haematol 2003;122:695-717 3. Jaffe ES, Harris NL, Stein H, et al:
World Health Organization Classification of Tumours. Pathology and Genetics. Tumours of the
Haematopoietic and Lymphoid Tissues. 2001, pp 291-302
Current as of January 4, 2013 7:15 pm CST 800-533-1710 or 507-266-5700 or MayoMedicalLaboratories.com Page 1072