(Reproduced by permission from Medicare Focus, July, 1997, pp. 49 - 55.)

Medicare Part A
Local Medical Review Policy
Serum Magnesium

Policy Number: A97-11

Description

Magnesium is a mineral required by the body for the use of adenosine triphosphate (ATP) as a source of energy. It is also necessary for neuromuscular irritability and blood clotting. Magnesium deficiency produces neuromuscular disorders. It may cause weakness, tremors, tetany, and convulsions. Hypomagnesemia is associated with hypocalcemia, hypokalemia, long-term hyperalimentation, intravenous therapy, diabetes mellitus, especially during treatment of ketoacidosis, alcoholism and other types of malnutrition, malabsorption, hyperparathyroidism, dialysis, pregnancy, and hyperaldosteronism. The following are other conditions which may cause magnesium deficiencies:

• Renal loss of magnesium occurs with cisplatinum therapy.
• Hypomagnesemia may also be induced by amphotericin toxicity.
• Magnesium deficiency is described with cardiac arrhythmias. The concept that magnesium may cause arrhythmias is repeatedly expressed.

Type of Bill: 12X, 13X, 14X, 22X, 23X, 71X, 74X, 75X

Revenue Codes: 300 - 319

Indications

• Utilization of certain cardiac drugs which cause adverse effects in the presence of low magnesium (i.e., Quinidine, Procainamide, and Norpace). Patients taking these drugs should have their magnesium checked approximately once every six months.
• Long term parenteral nutrition: Patients on long term parenteral nutrition that are otherwise asymptomatic should have a serum magnesium checked monthly.
• Malabsorption syndromes: The frequency should depend on the severity of the syndrome, but once the patient's level is stabilized, a monthly check should be adequate.
• Renal loss secondary to diuretic use should be followed on a six-month basis.
• Chronic alcoholism, diabetic acidosis, and renal tubular acidosis: These patients should be followed on an as-needed basis according to their symptomatology. Without symptoms, they should be checked no more than annually.
• Chronic diarrhea, otherwise unexplained and persistent, should have a magnesium check once it is stabilized on a two to three month basis.
• Prolonged nasogastric suction greater than five days should have a magnesium check every two to three weeks.
• Cisplatinum treatment: Checked on a monthly basis during the therapeutic regimen.
• Patients receiving IV magnesium therapy for a low serum level should have it checked as indicated by the dose and renal function of the patient.
• Patients with hypocalcemia should have a magnesium check. If the hypocalcemia persists, the level should probably be checked on a six-month basis as long as the patient does not have symptoms of arrhythmias which would warrant closer follow up.
• Lethargy and confusion which are not otherwise explained: Once a patient has been diagnosed with processes such as Alzheimer's or psychotic depression, etc., there is no indication to follow their magnesium level on a regular basis.
• Patients receiving oral magnesium in the face of impaired renal function should have their magnesium level checked on a monthly basis.
• Pre-eclampsia
• Unexplained muscular paralysis
• Neuromuscular irritability
• Blood clotting
• Superventricular and ventricular arrhythmias, not otherwise classified

HCPCS Codes: 83735 Magnesium

Diagnosis Codes for Coverage

c 1996, Copyright, 1997 CPT Physicians' Current Procedural Terminology, American Medical Association

Category:

Pathology and Laboratory

HCFA's National Policy

Title XVIII of the Social Security Act, section 1862(a)(7). This section excludes routine physical examinations.

Title XVIII of the Social Security Act, section 1862(a)(1)(A). This section allows coverage and payment for only those services that are considered to be medically reasonable and necessary.

Reason for Denial

• Medicare will deny claims when the procedure is performed for screening purposes.
• Medicare will deny claims that are submitted with other than the specified "covered" indications found in the "Diagnosis Codes for Coverage" section of this policy.
• Medicare will deny claims when the ordering physician's documentation in the patient's medical record does not support medical necessity.

Non-covered Diagnosis Codes

Any code not listed under covered diagnosis.

Sources of Information

• Laboratory Test Handbook
• CMD Clinical Laboratory Workgroup

Coding Guides

ICD-9 diagnosis code V82.9 (Special screening of other conditions, unspecified condition) or comparable narratives should be used to indicate screening tests performed in the absence of a specified sign, symptom, or complaint. Use of V82.9 or comparable narrative will result in the denial of claims as non-covered screening services.

The claim(s) should be submitted with an ICD-9 diagnosis code which reflects at least one of the specified "covered" indications found in this policy. Failure to do so will result in denial of claims. The ICD-9 diagnosis code must be linked to the appropriate procedure.

Documentation Required

Documentation supporting the medical necessity should be legible, maintained in the patient's medical record, and must be made available to Medicare upon request. The test must be ordered by the patient's attending or consulting physician.

If documentation is requested for review, submit the following:

• History and Physical;
• MD orders/progress notes
• Diagnosis/reason for test
• Test results
• Itemization of charges

Documentation of the medical necessity of the test must be retained in the ordering physician's patient medical record. Documentation should state the signs/symptoms/ or diagnosis which caused the need for the test procedure. Documentation must be made available to Medicare upon request. Failure to do so, may result in denial of claims.

Comments

This policy is being adapted from the Carrier policy. It does not represent the sole opinion of the Intermediary/Medical Director. This policy was developed in consultation with the medical community via the Carrier Advisory Committee.