Sorted By Test Name - Mayo Medical Laboratories

CTU
8513
FCDC
88536
Creatinine, Urine
Clinical Information: Creatinine is formed from the metabolism of creatine and phosphocreatine,
both of which are principally found in muscle. Thus the amount of creatinine produced is in large part
dependent upon the individual's muscle mass and tends not to fluctuate much from day-to-day. Creatinine
is not protein-bound and is freely filtered by glomeruli. All of the filtered creatinine is excreted in the
urine. Renal tubular secretion of creatinine also contributes to a small proportion of excreted creatinine.
Although most excreted creatinine is derived from an individual's muscle, dietary protein intake,
particularly of cooked meat, can contribute to urinary creatinine levels. The renal clearance of creatinine
provides an estimate of glomerular filtration rate.
Useful For: Urinary creatinine, in conjunction with serum creatinine, is used to calculate the creatinine
clearance, a measure of renal function.
Interpretation: 24-Hour urinary creatinine determinations are principally used for the calculation of
creatinine clearance. Decreased creatinine clearance indicates decreased glomerular filtration rate. This
can be due to conditions such as progressive renal disease, or result from adverse effect on renal
hemodynamics that are often reversible including certain drugs or from decreases in effective renal
perfusion (eg, volume depletion or heart failure). Increased creatinine clearance is often referred to as
"hyperfiltration" and is most commonly seen during pregnancy or in patients with diabetes mellitus,
before diabetic nephropathy has occurred. It also may occur with large dietary protein intake.
Reference Values:
15-25 mg/kg of body weight/24 hours
Reported in unit of mg/specimen
Clinical References: 1. Newman DJ, Price CP: Renal function and nitrogen metabolites. In Tietz
Textbook of Clinical Chemistry. 3rd edition. Edited by CA Burtis, ER Ashwood. Philadelphia, WB
Saunders, 1999, pp 1204-1270 2. Kasiske BL, Keane WF: Laboratory assessment of renal disease:
clearance, urinalysis, and renal biopsy. In The Kidney. 6th edition. Edited by BM Brenner. Philadelphia,
WB Saunders, 2000, pp 1129-1170
Cri-du-chat Syndrome, 5p15.2 Deletion, FISH
Clinical Information: Cri-du-chat syndrome is associated with a deletion on the short arm of
chromosome 5 (5p-). The syndrome can be suspected in infants with a plaintive, mewing cry, low birth
weight, and failure to thrive. The weak kittenlike cry that gives name to the syndrome is at least partly due
to anatomic abnormalities of the larynx and although the cry changes with time, it does not become
normal. Facial features include microcephaly, round face, low-set ears, strabismus, hypertelorism
(wide-set eyes), and epicanthus (a vertical fold of skin on either side of the nose). The hands and feet are
small, and the hands often have a single crease extending across the palm (simian crease). With age,
premature gray hair, dental malocclusion, inguinal hernia, distasis recti, (a separation of the left and right
side of the rectus abdominis muscle), and scoliosis are common. Affected individuals†intelligence
varies widely from mild-to-severe mental retardation. FISH studies are highly specific and do not exclude
other chromosome abnormalities. We recommend that patients suspected of having cri-du-chat syndrome
also have conventional chromosome studies (CMS/8696 Chromosomes Analysis, for Congenital
Disorders, Blood) performed to rule out other chromosome abnormalities or translocations.
Useful For: As an aid in the diagnosis of cri-du-chat syndrome, in conjunction with CMS/8696
Chromosome Analysis, For Congenital Disorders, Blood Detecting cryptic translocations involving
5p15.2 that are not demonstrated by conventional chromosome studies
Interpretation: Any individual with a normal signal pattern (2 signals) in each metaphase is
considered negative for a deletion in the region tested by this probe (see Cautions). Any patient with a
FISH signal pattern indicating loss of the critical region will be reported as having a deletion of the region
tested by this probe.
Reference Values:
An interpretive report will be provided.
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