Sorted By Test Name - Mayo Medical Laboratories

TTIG
82506
DHVD
8822
Tetanus Toxoid IgG Antibody Assay, Serum
Clinical Information: Tetanus is a nervous system disease characterized by severe muscle spasms
caused by the toxin tetanospasmin that is produced by Clostridium tetani organisms. The disease is
preventable by vaccination with tetanus toxoid (formaldehyde-treated tetanospasmin). Tetanus toxoid is
an excellent immunogen; it stimulates development of antitetanus toxoid antibodies. Subsequent to
vaccination, a patient's immunological response may be assessed by determining the presence of tetanus
toxoid antibody levels in the serum. An absence of antibody formation postvaccination may relate to
immune deficiency disorders, either congenital, acquired, or iatrogenic due to immunosuppressive drugs.
Useful For: Assessment of an antibody response to tetanus toxoid vaccine May be used to aid
diagnosis of immunodeficiency
Interpretation: Results > or =0.16 IU/mL suggest a vaccine response. Some cases of tetanus, usually
mild, occasionally have been observed in patients who have a measurable serum level of 0.01 to 1.0
IU/mL.
Reference Values:
The minimum level of protective antibody in the normal population is between 0.01 and 0.15 IU/mL. The
majority of vaccinated individuals should demonstrate protective levels of antibody >0.15 IU/mL.
Clinical References: 1. Bleck TP: Clostridium tetani (tetanus). In Principals and Practice of
Infectious Disease. 5th edition. Edited by GL Mandell, JE Bennett, R Dolin. Churchill Livingstone,
Philadelphia, 2000, pp 2537-2543 2. Gergen PJ, McQuillan GM, Kiely M, et al: A population-based
serologic survey of immunity to tetanus in the United States. N Engl J Med 1995;332:761-766 3.
Bjorkholm B, Wahl M, Granstrom M, Hagberg L: Immune status and booster effects of low doses of
tetanus toxoid in Swedish medical personnel. Scand J Infect Dis 1994;26:471-475 4. Ramsay ME, Corbel
MJ, Redhead K, et al: Persistence of antibody after accelerated immunization with
diptheria/tetanus/pertussis vaccine. Br Med J 1991;302:1489-1491 5. Rubin RL, Tang FL, Chan EK, et al:
IgG subclasses of autoantibodies in systemic lupus erythematosus. Sjogren's syndrome, and drug-induced
autoimmunitiy. J Immunol 1986;137:2522-2527 6. Simonsen O, Bentzon MW, Heron I: ELISA for the
routine determination of antitoxic immunity to tetanus. J Biol Stand 1986;14:231-239
1,25-Dihydroxyvitamin D, Serum
Clinical Information: Vitamin D is a generic designation for a group of fat-soluble, structurally
similar sterols including ergocalciferol D2 from plants and cholecalciferol D3 from animals. Vitamin D in
the body is derived from 2 sources: exogenous (dietary: D2 and D3) and endogenous (biosynthesis: D3).
Endogenous D3 is produced in the skin from 7-dehydrocholesterol, under the influence of ultraviolet
light. Both forms of vitamin D are of similar biologic activity. Vitamin D is rapidly metabolized in the
liver to form 25-hydroxy (OH) vitamin D. Additional hydroxylation of 25-OH vitamin D takes place in
the kidney by 1-alpha hydroxylase, under the control of parathyroid hormone, to yield 1,25-dihydroxy
vitamin D. 1,25-Dihydroxy vitamin D is the most potent vitamin D metabolite. It stimulates calcium
absorption in the intestine and its production is tightly regulated through concentrations of serum calcium,
phosphorus, and parathyroid hormone. 1,25-Dihydroxy vitamin D levels may be high in primary
hyperparathyroidism and in physiologic hyperparathyroidism secondary to low calcium or vitamin D
intake. Some patients with granulomatous diseases (eg, sarcoidosis) and malignancies containing
nonregulated 1-alpha hydroxylase in the lesion may have elevated 1,25-dihydroxy vitamin D levels and
hypercalcemia. 1,25-Dihydroxy vitamin D levels are decreased in hypoparathyroidism and in chronic
renal failure. While 1,25-dihydroxy vitamin D is the most potent vitamin D metabolite, levels of the
25-OH forms of vitamin D more accurately reflect the bodyâ€s vitamin D stores. Consequently,
25HDN/83670 25-Hydroxyvitamin D2 and D3, Serum is the preferred initial test for assessing vitamin D
status. However, in the presence of renal disease, 1,25-dihydroxy vitamin D levels may be needed to
adequately assess vitamin D status.
Useful For: As a second-order test in the assessment of vitamin D status, especially in patients with
renal disease Investigation of some patients with clinical evidence of vitamin D deficiency (eg, vitamin
D-dependent rickets due to hereditary deficiency of renal 1-alpha hydroxylase or end-organ resistance to
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