Carnitine Profile, Quantitative, Urine

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Condition Description

Carnitine deficiency can be from a primary defect or can be a secondary effect. Primary carnitine deficiency can be the result of several metabolic conditions including Carnitine Uptake Deficiency (CUD), Carnitine Acylcarnitine Transporter (CACT) Deficiency, Carnitine Palmitoyltransferase I (CPT I) Deficiency, Carnitine Palymitoltransferase II (CPTII) Deficiency. Primary carnitine deficiency can present with:
  • hypoketotic hypoglycemia encephalopathy
  • hepatomegaly
  • cardiomyopathy
  • muscle weakness
  • gastrointestinal dysmotility
  • hypochromic anemia
Secondary carnitine deficiency results from another metabolic disorder, such as another fatty acid oxidation disorder, or an organic acidemias leading to carnitine depletion secondary to the formation of acylcarnitines for excretion of accumulating by products. Secondary carnitine deficiency can present with symptoms of:
  • encephalopathy
  • hypotonia
  • hepatomegaly
  • cardiac hypertrophy
  • failure to thrive
  • hypoglycemia
  • ketoacidosis
  • hyperammonemia

Indications

This test is indicated for patients with:
  • lethargy/hypotonia
  • myopathy (cardiac/skeletal)
  • clinical suspicion of a fatty acid oxidation defect and an organic acidemia
  • renal dysfunction
  • positive newborn screening result with decreased free carnitine and/or abnormal acylcarnitine profile
The test is most commonly performed in serum or plasma. A urine carnitine profile is recommended in addition to a plasma carnitine profile in patients suspected of having a primary disorder of carnitine transport.

Methodology

Electrospray Tandem Mass Spectrometry (MS/MS).

Detection and Reference Range

Detection
Detection of carnitine deficiency can be sensitive to the age and eating status of the patient.
Reference Range

Total Carnitine (nmol/mg creatinine)
Free Carnitine (FC) (nmol/mg creatinine)
Acylcarnitine (AC) (nmol/mg creatinine)
AC / FC
2 - 8 Years
60 - 295
35 - 93
42 - 232
0 - 4.4
> 8 Years
187 - 313
16 - 158
153 - 226
0 - 4.4

Specimen Requirements

Additional Specimen Collection/Handling Instructions Required for this Test
For diagnostic purposes, specimens should ideally be collected during time of acute illness as abnormal metabolite levels may decrease, sometimes to near normal concentrations, when patient is well.

Type: Urine

Specimen Requirements:

In a clean container without preservatives: 2-5 ml. Freeze.

Fasting or first void sample is preferable.

Specimen Collection and Shipping: Ship frozen sample on dry ice with overnight delivery.

Special Instructions

Please indicate any medications or dietary changes on the test requisition form.
  • Organic Acids Profile (OA)
  • Acylcarnitine Profile (AR) - Plasma

How to Order