Secondary carnitine deficiency

There are two recognized types of carnitine deficiency—primary and secondary. 

Carnitine deficiency may also be secondary to a variety of conditions. 

The answer is D. The most likely diagnosis in this case is CPT-II deficiency, although this is apparently a fairly mild case. The patient s muscle weakness and brown urine (myoglobinuria) are characteristic of this disorder. CPT-I deficiency would most likely manifest as liver dysfunction. A secondary form of carnitine deficiency due to exogenous factors such as malnutrition, infection, or dialysis, is unlikely. MCAD ordinarily manifests within the first 3-5 years of life. The patient s normal stature is inconsistent with Marfan syndrome, which is characterized by tall stature and very long bones in the extremities. 

In another case, there was late-onset lipid storage myopathy, with secondary carnitine deficiency (SED-13, 150) (1187). 

Carnitine is present in biological systems as both carnitine and acylcarnitines generated in tissues (see next section). Carnitine deficiency may be a primary defect due to a genetic defect in carnitine transport systems or may be secondary to other metabolic derangements. Normal carnitine homeostasis requires reabsorption of carnitine in the renal tubule via a specific transport protein. This same transport protein is responsible for the accumulation of carnitine in heart and skeletal muscle. If this transport system is not functional, then carnitine cannot reach tissues, and primary carnitine... 

Turnbull DM, Bartlett K, Stevens DL, Alberti KG, Gibson GJ, Johnson MA, et al. Short-chain acyl-CoA dehydrogenase deficiency associated with a lipid-storage myopathy and secondary carnitine deficiency. N Engl J Med 1984 311 1232-6. 

Acylcarnitine concentrations are more helpful in secondary causes of carnitine deficiency. When only total and free concentrations are available, the free is subtracted from the total to give the acylcarnitine concentration. 

Short-chain acyl-CoA dehydrogenase deficiency associated with a lipid-storage myopathy and secondary carnitine deficiency. 

Infante, J.P., and Huszagh, V.A. (2000) Secondary Carnitine Deficiency and Impaired Docosahexaenoic (22 6n-3) Acid Synthesis A Common Denominator in the Pathophysiology of Diseases of Oxidative Phosphorylation and Beta-Oxidation, FEBS Lett. 468,1-5. 

A secondary carnitine deficiency due to accumulation of propionyl-CoA and increased concentration of acylcamitines is also common [13]. Superficial desquamation, alopecia, and corneal ulcerations similar to staphylococcal scalded skin syndrome or acrodermatitis enteropathica-like syndrome, typically associated with diarrhea, may be seen secondary to acute protein malnutrition or essential amino acid deficiency, especially isoleucine deficiency [34, 52-54]. Immune dysfunction has also been suggested with an increased risk for viral or bacterial infections, but good studies are lacking [34]. Chronic moniliasis has been described and reflects the effect of propionyl-CoA and methylmalonate on T-cell number and function [7], Finally, acute and chronic pancreatitis, osteopenia or osteoporosis, and ovarian failure may also occur the etiologies of which remain unclear [3, 7, 24, 34, 36,47, 55-59],... 

Since L-camitine conjugates with toxic acyl-CoA metabolites produced in PROP and MM A, patients often develop a secondary carnitine deficiency. To prevent this, L-camitine in doses of 100-300 mg/ kg/day is prescribed on a routine basis [5, 11]. Some medical foods designed for PROP and MMA contain L-camitine, and this needs to be considered when determining the amount of supplement to prescribe. The IV form of L-camitine is often used during hospitalization for acute illness [3]. 

Most patients with PROP and MMA are prescribed L-camitine supplements to prevent a secondary carnitine deficiency, and routine measurement of plasma or serum carnitine is recommended [5]. This analysis will include total carnitine, carnitine esters (esterified), and free carnitine concentrations. Low concentrations of free carnitine suggest a need to increase the supplementation dose. With supplementation, the total and ester fractions are often elevated. 

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