VAD in Pakistan is considerably pervasive, thus declaring Pakistan as a country with "severe subclinical deficiency
of vitamin A.
It is only in the severely malabsorptive disorders such as PA, not subclinical deficiency
, that neurological deterioration following folic acid therapy has been described.
12] deficiency is frequently misperceived as a single, progressive continuum, a perception that blurs the many substantive differences between subclinical deficiency (isolated, minimal biochemical abnormalities of variable permanence in persons without signs or symptoms) and clinical deficiency (typically malabsorptive, progressive, and symptomatic, as in pernicious anemia) (2).
12] measurement, although an imperfect marker, offers a diagnostic sensitivity of 95%-97%, compared with only 38%-39% for subclinical deficiency (2).
More common is biochemical, subclinical deficiency, usually in elderly people in whom serum B12 above 200 pmol/L can be accompanied by raised serum methylmalonate (MMA) and homocysteine.
The causes of subclinical deficiency are also not well understood in many cases.
A subclinical deficiency
of magnesium might make you more susceptible to noise-induced hearing loss, suggest several animal studies and one human trial.
Lack of a simple screening test to measure subclinical deficiency
adds to this problem.
In a field setting of VAD-endemic northern Kenya, RBP in DBS prepared from venous blood samples of individuals with a wider range of VA status, including subclinical deficiency
, also appeared to withstand storage at ambient temperatures for 6 weeks in a sealed plastic bag with desiccant and produced results that correlated well with serum-retinol values.
Laboratory tests are used to detect subclinical deficiency
states or to confirm a clinical diagnosis.