Subclinical

McConnell R, Pacheco F, Wahlberg K, et al. 1999. Subclinical health effects of environmental pesticide contamination in a developing country Cholinesterase depression in children. Environ Res A81 87-91. 

Experimental animals exposed to sublethal doses of cyclodienes show a similar picture, with changes in EEG patterns, disorientation, loss of muscular coordination and vomiting, as well as convulsions, the latter becoming more severe with increasing doses (Hayes and Laws 1991). It is clear from these wide-ranging studies that a number of neurotoxic effects can be caused by cyclodienes at levels well below those that are lethal. In the human studies described here, subclinical symptoms were frequently reported when dieldrin blood levels were in the range 50-100 pg/L, an order of magnitude below those associated with lethal intoxication. 

Cytomegalovirus (CMV) Enveloped, icosahedral particles 150nm in diameter CMV is generally acquired in childhood as a subclinical infection. About 50% of adults carry the virus in a dormant state in white blood cells. The virus can cause severe disease (pneumonia, hepatitis, encephalitis) in immunocompromised patients. Primary infections during pregnancy can induce serious congenital abnormalities in the fetus... 

This is produced as a result of an antigenic stimulus. This stimulus may occur naturally by means of a clinical or subclinical infection, or artificially by the deliberate introduction into the body ofthe appropriate antigen in the form ofa vaccine or toxoid (Chapter 16). This type of immunity is normally long-lasting. 

Rubella is a mild, often subclinical infection that is common amongst children aged between 4 and 9 years. Infection during the first trimester of pregnancy brings with it a... 

Nagaya T, IshikawaN, Hata H, et al. 1993. Subclinical and reversible hepatic effects of occupational exposure to trichloroethylene. Int Arch Occup Environ Health 64 561-563. 

Rasmussen K, Brogren CH, Sabroe S. 1993b. Subclinical affection of liver and kidney function and solvent exposure. Int Arch Occup Environ Health 64 445-448. 

The goals of treatment of status epilepticus include the cessation of any seizure activity, both clinical and subclinical, and the prevention of further seizures. Ideally, this is accomplished through directed pharmacotherapy with minimization of any side effects or adverse reactions. Complications ofSE should also be treated. 

Discuss the prevalence of thyroid disorders, including subclinical (mild) and overt (typical signs and/or symptoms present) hypothyroidism and hyperthyroidism. 

The assessment of patients for thyroid disorders entails a history and physical examination. In many patients with subclinical or mild thyroid disease, there may be an absence of specific signs and symptoms, and the physical examination may be normal. Various diagnostic tests can be used, including serum thyroid hormone(s), TSH, and thyroid antibody levels and imaging techniques to evaluate patients for thyroid disorders. Normal values for selected laboratory tests are given in Table 41-1. 

Anti-TPOAb Less than 1 00 units/mL Present in autoimmune hypothyroidism predicts more rapid progression from subclinical to overt hypothyroidism... 

The laboratory assessment of patients with suspected thyroid disorders must be based on the continuum of disease from subclinical or mild to overt (Fig. 41-2). 

A TSH level of 4.5 to 10 milliunits/L constitutes mild or sub-clinical hypothyroidism, and some patients with a TSH level of 2.5 to 4.5 milliunits/L also may be mildly hypothyroid. A TSH level greater than 10 milliunits/L signifies overt hypothyroidism." The free T4 level will be normal (0.7-1.9 ng/dL or 9.0-24.5 pmol/L) in mild or subclinical hypothyroidism and low (less than 0.7 ng/dL or 9.0 pmol/L) in patients with obvious signs and/or symptoms. 

LT4 is indicated for patients with overt hypothyroidism.22 However, the need for treatment is controversial in patients with mild or subclinical disease (TSH less than 10 milli-units/L). There are no large clinical trials that show an outcome benefit with treating these patients, and the therapeutic decision must be individualized.1,23 Many patients with subclinical hypothyroidism do, in fact, have subtle symptoms that improve with LT4 replacement. If the patient s serum cholesterol is elevated,24 or if serum anti-TPOAbs are present, many clinicians recommend LT4 therapy. 

Patients with mild or subclinical hypothyroidism do not need to be started on the full replacement dose because they still have some endogenous hormone production. Start these patients on 25 to 50 meg/day, and titrate every 6 to 8 weeks based on TSH levels. Over time, it is likely that the LT4 dose will need to be increased slowly as the patient s thyroid gland loses residual function. 

Hyperthyroidism is much less common than hypothyroidism. In NHANES III,1 1.3% of the population was hyperthyroid (0.5% overt, 0.8% subclinical), with the highest incidences in women overall and in men and women in the 20 to 39 and over 80 years of age groups. The Colorado Thyroid Health Study2 showed a hyperthyroid incidence of 2.2% (2.1% subclinical). 

Subclinical or mild thyrotoxicosis is defined as a low TSH with a normal FT4 level. While there may be few or no symptoms in these patients, there are several areas of concern.31,32 Many patients will progress to overt thyrotoxicosis. Patients with subclinical hyperthyroidism have been shown to suffer long-term cardiovascular and bone sequelae. In a 10-year follow-up of 2007 patients over age 60,33 patients with an undetectable TSH level had a 3.1-fold increased risk of atrial fibrillation versus those with a normal TSH. In a different 10-year follow-up study34 of... 

The growth and spread of thyroid carcinoma is stimulated hy TSH. An important component of thyroid carcinoma management is the use ofLT4 to suppress TSH secretion. Early in therapy, patients receive the lowest LT4 dose sufficient to fully suppress TSH to undetectable levels. Controlled trials show that suppressive LT4 therapy reduces tumor growth and improves survival. These patients are purposefully overtreated with LT4 and rendered subclinically hyperthyroid. Postmenopausal women should receive aggressive osteoporosis therapy to prevent LT4-induced bone loss. Other thyrotoxic complications, such as atrial fibrillation, should be monitored and managed appropriately. 

Diarrhea is an early symptom and occurs only in 50% of cases. Intestinal hemorrhage or perforation, leukopenia, anemia, and subclinical disseminated intravascular coagulopathy may be seen. 

Subclinical warts Subclinical warts may be identified through colonoscopy, biopsy, acetic acid application, or laboratory serology. However, early treatment has not been linked to a favorable effect during the course of therapy in the index patient or the partner with regard to reduction of the transmission rate. 

It has been postulated that Chlamydia may produce a heat shock protein that causes tissue damage through a delayed hypersensitivity reaction. C. trachomatis may also possess DNA evidence of toxin-like genes that code for high-molecular-weight proteins with structures similar to Clostridium difficile cytotoxins, enabling inhibition of immune activation. This may explain the observation of a chronic C. trachomatis infection in subclinical PID. 

The treatment for ALL consists of three main elements remission induction, intensification (consolidation), and continuation (maintenance) phases of treatment.3 Therapy to eradicate subclinical CNS leukemia is also an integral part of therapy for ALL (Table 92-7). 

Since rapid death may occur with certain infections in neutropenic patients, prompt and emergent treatment is indicated. The primary goal is to prevent morbidity and mortality during the neutropenic period. This is accomplished by effectively treating subclinical infections or established infections. 

Coop, R. (1986) Subclinical parasitism The insidious effects of roundworms on lamb performance. Science and Quality Lamb Production, 24-5, Agricultural and Food Research Council, London. 

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