Diagnostic utility of lactate dehydrogenase levels in patients receiving aerosolized pentamidine

The Biochemical and Clinical Perspectives of Lactate Dehydrogenase: An Enzyme of Active Metabolism

BACKGROUND

Lactate dehydrogenase (LDH) is a group of oxidoreductase isoenzymes catalyzing the reversible reaction between pyruvate and lactate. The five isoforms of this enzyme, formed from two subunits, vary in isoelectric points and these isoforms have different substrate affinity, inhibition constants and electrophoretic mobility. These diverse biochemical properties play a key role in its cellular, tissue and organ specificity. Though LDH is predominantly present in the cytoplasm, it has a multi-organellar location as well.

OBJECTIVE

The primary objective of this review article is to provide an update in parallel, the previous and recent biochemical views and its clinical significance in different diseases.

METHODS

With the help of certain inhibitors, its active site three-dimensional view, reactions mechanisms and metabolic pathways have been sorted out to a greater extent. Overexpression of LDH in different cancers plays a principal role in anaerobic cellular metabolism, hence several inhibitors have been designed to employ as novel anticancer agents.

DISCUSSION

LDH performs a very important role in overall body metabolism and some signals can induce isoenzyme switching under certain circumstances, ensuring that the tissues consistently maintain adequate ATP supply. This enzyme also experiences some posttranslational modifications, to have diversified metabolic roles. Different toxicological and pathological complications damage various organs, which ultimately result in leakage of this enzyme in serum. Hence, unusual LDH isoform level in serum serves as a significant biomarker of different diseases.

CONCLUSION

LDH is an important diagnostic biomarker for some common diseases like cancer, thyroid disorders, tuberculosis, etc. In general, LDH plays a key role in the clinical diagnosis of various common and rare diseases, as this enzyme has a prominent role in active metabolism.

Behandlung von Patienten mit HIV-Infektion auf der Intensivstation

HIV-infizierte Patienten können aus einer Reihe von Indikationen heraus der Intensivbehandlung bedürfen (·Abb. 66.1; [7, 17, 19, 33, 41, 44, 51]). In 50–75% der Fälle stellt akutes respiratorisches Versagen die Indikation für die Behandlung HIV-Infizierter auf der Intensivstation dar [7, 17, 19, 33, 41, 44, 51]. Bei 55–90% dieser Patienten mit intensiv behandlungsbedürftigem respiratorischen Versagen stellt Pneumocystis carinii das für die Erkrankung verantwortliche Pathogen dar [7, 33, 44].

The association of serum lactate dehydrogenase level with selected opportunistic infections and HIV progression

BACKGROUND

The purpose of this study was to determine the association of serum lactate dehydrogenase (LDH) levels with certain opportunistic infection and to determine an association between LDH levels and CD4+ lymphocyte counts.

METHOD

We studied 352 patients retrospectively with HIV infection and one of the following infections: histoplasmosis; toxoplasmosis; tuberculosis (pulmonary and disseminated); bacterial pneumonia; Pneumocystis carinii pneumonia. Demographic and clinical data were obtained from the Adult Spectrum of Diseases (ASD) database in New Orleans. Bivariate and multivariate analysis were used to determine the association between LDH levels and opportunistic infections and CD4+ lymphocyte counts.

RESULTS

Patients with a serum LDH level <225 IU/L had a mean CD4+ lymphocyte count of 159/dl (SE 19.3) as compared to patients with a serum LDH level > or =225 IU/L, who had a mean CD4+ lymphocyte count of 58/dl (SE 6.9) (P<0.01). Non-Caucasian race, a diagnosis of histoplasmosis, disseminated tuberculosis or Pneumocystis carinii pneumonia, and CD4+ lymphocyte count were significantly associated with a serum LDH level > or =225 IU/L in the bivariate analysis. In a multivariate analysis, after controlling for race and CD4+ lymphocyte count, the only diagnoses that were significantly associated with the serum LDH level were definitive Pneumocystis carinii pneumonia and toxoplasmosis. Having a higher LDH level was not associated with early mortality.

CONCLUSIONS

Although not diagnostic, serum LDH levels could be used as an adjunctive marker in certain opportunistic infections. There is an inverse relationship between serum LDH levels and CD4+ lymphocyte counts in this group.

Pulmonary paracoccidioidomycosis misdiagnosed as Pneumocystis pneumonia in an immunocompromised host

Yeast cells of Paracoccidioides brasiliensis can resemble the cysts of Pneumocystis carinii in smears stained with Grocott's modification of the Gomori methanamine silver stain. Furthermore, P. brasiliensis can cross-react in material stained with a widely used P. carinii immunofluorescent stain which uses monoclonal antibodies. The need to differentiate P. brasiliensis and P. carinii will become more important as the increasing incidence of immunosuppression results in the reactivation of latent P. brasiliensis infections.

AIDS and the lung

Respiratory symptoms are common in HIV-infected persons. The challenge facing clinicians is to determine whether these respiratory symptoms are due to an opportunistic infection or to a chronic process, such as asthma, chronic bronchitis, bronchiectasis, or emphysema. This article reviewed the clinical presentation, diagnosis, and treatment of two important opportunistic infections, PCP and bacterial pneumonia. It also reviewed the current data on obstructive lung diseases as they relate to HIV.