HMNA - Clinical: Heavy Metals, Nails

Test Catalog

Test Name

Test ID: HMNA    
Heavy Metals, Nails

Useful For Suggests clinical disorders or settings where the test may be helpful

Detection of nonacute arsenic, mercury, and lead exposure

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

ARSENIC

Arsenic circulating in the blood will bind to protein by formation of a covalent complex with sulfhydryl groups of the amino acid cysteine. Keratin, the major structural protein in hair and nails, contains many cysteine residues and, therefore, is one of the major sites for accumulation of arsenic. Since arsenic has a high affinity for keratin, the concentration of arsenic in nails is higher than in other tissues.

 

Several weeks after exposure, transverse white striae, called Mees' lines, may appear in the fingernails

 

MERCURY

Once absorbed and circulating, mercury becomes bound to numerous proteins, including keratin. The concentration of mercury in nails correlates with the severity of clinical symptoms. If the nails can be segregated by length, such an exercise can be useful in identifying the time of exposure.

 

LEAD

Nail analysis of lead can be used to corroborate blood analysis.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

ARSENIC

0-15 years: not established

> or =16 years: 0.0-0.9 mcg/g of nails

 

LEAD

0.0-3.9 mcg/g of nails

Reference values apply to all ages.

 

MERCURY

0-15 years: not established

> or =16 years: 0.0-0.9 mcg/g of nails

Interpretation Provides information to assist in interpretation of the test results

Nails grow at a rate of approximately 0.1 inch/month. Nail keratin synthesized today will grow to the distal end in approximately 6 months. Thus, a nail specimen collected at the distal end represents exposure of 6 months ago.

 

ARSENIC

Nail arsenic above 1.0 mcg/g dry weight indicates excessive exposure. It is normal for some arsenic to be present in nails, as everybody is exposed to trace amounts of arsenic from the normal diet.

 

The highest hair or nail arsenic observed at Mayo Clinic was 210 mcg/g dry weight in a case of chronic exposure that was the cause of death.

 

MERCURY

Normally, nails contain less than 1 mcg/g of mercury; any amount above this indicates that exposure to more than normal amounts of mercury has occurred.

 

LEAD-

Normally, the nail lead content is below 4.0 mcg/g. Nail lead content above 10.0 mcg/g indicates significant lead exposure.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Hindmarsh JT, McCurdy RF: Clinical and environmental aspects of arsenic toxicity. Crit Rev Clin Lab Sci 1986;23:315-347

2. Strumylaite L, Ryselis S, Kregzdyte R: Content of lead in human hair from people exposed to lead. Int J Hyg Environ Health 2004;207:345-351

3. Barbosa F, Tanus-Santos J, Gerlach R, Parsons P: A critical review of biomarkers used for monitoring human exposure to lead: advantages, limitations, and future needs. Environ Health Perspect 2005;113:1669-1674

4. Sanna E, Liguori A, Palmes L, et al: Blood and hair lead levels in boys and girls living in two Sardinian towns at different risks of lead pollution. Ecotoxicol Environ Saf 2003;500:293-299

Special Instructions and Forms Library of PDFs including pertinent information and consent forms, specimen collection and preparation information, test algorithms, and other information pertinent to test