Financial unbundling reduces outpatient laboratory use.

Previous studies have examined methods of reducing laboratory use, without great success. We studied the effects of the financial unbundling of clinical biochemistry determinations in a university outpatient clinic. After eliminating the charge structure that promoted panel use, the ordering of chemistry 19 panels fell dramatically, accompanied by an increase in orders for electrolyte and chemistry 6 panels. The total number of biochemical assay determinations fell by one third after this administrative intervention. Only orders for potassium and creatinine measurements remained relatively unchanged and eventually increased. The ordering of five analytes of the chemistry 19 profile was reduced by at least 50%. Reassessment of the intervention six months later demonstrated the sustained decline in laboratory use. We conclude that physicians are attuned to price inefficiencies in basic laboratory testing and can alter their ordering behavior accordingly. Facilities can change patterns of use by altering charge structures alone. The decline in laboratory testing also indicates that physicians receive unnecessary clinical data when they order biochemical profiles. Financially bundled chemistry profiles could be replaced by physiologically based test groupings.

Quantification of vitamin D receptor mRNA by competitive polymerase chain reaction in PBMC: lack of correspondence with common allelic variants.

It has been recently claimed that polymorphism for the vitamin D receptor (VDR) influences several aspects of calcium and bone metabolism. To evaluate the physiologic plausibility of these claims, we compared the abundance of the VDR mRNA in peripheral blood mononuclear cells (PBMCs) between different VDR genotypes using a quantitative reverse transcribed polymerase chain reaction-based method. The method is based on the coamplification of VDR cDNA and an internal standard consisting of known concentrations of a human VDR CDNA mutated at a BglII restriction site; the interassay coefficient of variation is 11%. To validate the method, we made use of earlier receptor binding studies indicating that normal human monocytes and activated, but not resting, lymphocytes expressed the VDR. The concentration of the VDR mRNA was 10(-8) to 10(-7) g/g of total RNA in cell-sorted monocytes and in in vitro activated lymphocytes, but only 10(-12) g/g of total mRNA in resting lymphocytes, establishing that the VDR mRNA determined by our method in PBMCs is due to constitutive expression in monocytes. Following an initial genotype screening of 85 normal volunteers by polymerase chain reaction or restriction fragment length polymorphism analysis, 14 individuals with the Bb genotype, 12 with the bb genotype, and 12 with the BB genotype were selected. The concentration of the VDR mRNA, corrected for the number of monocytes, was similar among the three genotype groups, as were the other variables examined: serum calcitriol, serum osteocalcin, and vertebral and hip bone density. We conclude that VDR polymorphism does not affect the abundance of the VDR mRNA.

Plasma D-dimer: a useful tool for evaluating suspected pulmonary embolus.

Although ventilation-perfusion lung scanning is widely used in evaluating patients with suspected pulmonary embolus, additional rapid screening tests are needed to supplement scintigraphy in patients in whom the scan is indeterminate or the scan results are discordant with clinical suspicion. D-dimer is a fibrin degradation product which should be elevated in the presence of intravascular coagulation. We prospectively studied patients referred for lung scanning by obtaining a plasma D-dimer latex agglutination assay at the time of the scan. Of 64 patients who had pulmonary angiography to confirm the diagnosis, 16 were positive for pulmonary embolus and only one had a normal D-dimer. The D-dimer was normal in 27 of 48 patients without embolus and elevated in 21. Although an elevated D-dimer level is a nonspecific finding, we conclude that a normal D-dimer is a good negative predictor for pulmonary embolus, with a negative predictive value of 0.97.

Cytomegalovirus pneumonia in sickle cell disease.

Cytomegalovirus (CMV) pneumonia frequently occurs in immunocompromised hosts. Unlike encapsulated bacteria and Mycoplasma, CMV pneumonia has not been reported in sickle cell disease. We describe a case of a healthy young man with sickle cell thalassemia who died with CMV pneumonia.

Correlation of standardized serum protein determinations with calculated and measured colloid osmotic pressure.

The colloid osmotic pressure (COP) was measured on the serum of 250 individuals (healthy persons and patients) using a commercial oncometer. The total serum protein concentrations were measured by five methods, and the serum albumin concentrations were measured by four methods. The protein determinations were standardized as recommended by the Study Group on Proteins of the AACC Committee on Standards. The measured COP (mCOP) was correlated with each of the nine analytically determined protein concentrations. The mCOP also was correlated with a COP calculated (cCOP) from the Landis-Pappenheimer equation: cCOP = 2.1 (total protein [TP]) + 0.16 (TP)2 + 0.009 (TP)3. The authors found excellent linear correlations between mCOP and total protein concentration, and between mCOP and albumin concentration, when the protein determinations were standardized properly. The correlation between mCOP and protein concentrations was as good as the correlation between mCOP and cCOP in all cases. The serum albumin as determined by the DuPont ACA and mCOP gave the best linear relationship (r = 0.940) of the methods tested. Using the linear regression equation of albumin (ACA) versus mCOP, we were able to predict a cCOP to within +/- 3 mmHg for more than 95% of all samples tested.

Serum osmolality in acute intoxication: a prospective clinical study.

The authors prospectively performed simultaneous determinations of serum delta osmolality (delta-Osm), enzymic (alcohol dehydrogenase [ADH]) quantitation of serum ethanol (EtOH), and urine drug screens on 339 acutely intoxicated patients. In addition, the authors established reference ranges for measured and calculated serum osmolalities in a group of 55 healthy volunteers. The authors determined the clinical utility of the combined delta-Osm/ADH procedure for detecting the presence of EtOH or other low molecular weight (Mr) volatiles. In the reference population, the measured osmolality (M-Osm) and calculated osmolality (C-Osm) was 285.1 +/- 4.3 (SD) mOsm/kg and 287.4 +/- 5.1 (SD) mOsm/kg, respectively. The correlation between delta-OsM and serum EtOH was 0.968 in 151 patients in whom EtOH was detected. The presence of drugs in 67 (44%) patients or absence of drugs in 84 (55.6%) patients was shown to have no significant effect on the delta-Osm. The delta-Osm/ADH method failed to detect a volatile other than EtOH in only two cases (0.6%) or in addition to EtOH in three cases (0.9%). The concentrations of these volatiles were not clinically significant. The sensitivity for detecting EtOH by means of the delta-Osm calculation was 98.1% with a specificity of 98.2%. A disparity (delta-Osm greater than 10 mOsm/kg) between delta-Osm and the EtOH determination suggested a volatile other than EtOH in five cases (1.5%), which was confirmed by head-space gas chromatographic (GC-HS) analysis. A volatile in addition to EtOH in seven cases (2.1%) was suggested but not confirmed by GC-HS analysis. The delta-Osm/ADH procedure provides an efficient, rapid, and readily available method to evaluate the acutely intoxicated patient for the presence of EtOH and/or other low Mr volatiles.

Clinical comparison of immunoradiometric assays for intact versus beta-specific human chorionic gonadotropin.

Monoclonal immunoradiometric assays (IRMA) for human chorionic gonadotropin (hCG) are available for either intact hCG (IhCG) or beta subunit hCG (beta hCG). The authors evaluated the clinical applications of both methods. Serum samples (N = 180) were divided into the following five clinical groups: Group 1: elevated luteinizing hormone (LH), follicular stimulating hormone (FSH), and thyroid-stimulating hormone (TSH), which share alpha subunits with hCG; Group 2: pregnancy; Group 3: trophoblastic tumors; Group 4: malignancy; and Group 5: positive rheumatoid factor or anti-nuclear antibody (ANA). The values of beta hCG versus IhCG for Group 1 showed statistical significance but no clinical significance, indicating negligible cross-reactivity in the alpha subunit group. beta hCG values, although exceeding the IhCG values, correlated well (r = 0.97) in intrauterine pregnancies; however, these values were not believed to be clinically significant. There is negligible interference by alpha subunits, elevated rheumatoid factor, ANA, or malignancy in the determination of IhCG versus beta hCG. The authors conclude that either the IhCG or beta hCG assays may be used in clinical conditions in which a potential exists for interference of alpha subunits, autoantibodies, or heterophile antibodies or in malignancy.

Computerized calculation with osmolality and its automatic comparison with observed serum ethanol concentration.

The need to obtain blood alcohol levels in the differential diagnosis of the acutely intoxicated or unconscious patient often presents an emergency situation. By simultaneously determining the measured osmolality, the calculated osmolality, and the enzymatically-assayed ethanol level, the presence of alcohols other than ethanol can be recognized rapidly. A computer program has been written in FORTRAN to perform the necessary calculations, check for internal consistency, and alert the technologist if a disparity occurs.

Effect of supplemental dietary glutamine on methotrexate concentrations in tumors.

This study evaluated the effects of supplemental dietary glutamine (GLN) on methotrexate sodium concentrations in tumors and serum of sarcoma-bearing rats following the initiation of methotrexate. After randomization to a GLN diet (+GLN) or GLN-free diet (-GLN), tumor-bearing rats received 20 mg/kg of methotrexate sodium by intraperitoneal injection. The provision of supplemental GLN in the diet increased methotrexate concentrations in tumor tissues at 24 and 48 hours (38.0 +/- 0.20 nmol/g for the +GLN group vs 28.8 +/- 0.10 nmol/g for the -GLN group and 35.6 +/- 0.18 nmol/g for the +GLN group vs 32.5 +/- 0.16 nmol/g for the -GLN group, respectively). Arterial methotrexate levels were elevated only at 48 hours (0.147 +/- 0.007 microns/L for the +GLN group vs 0.120 +/- 0.006 microns/L for the -GLN group). Tumor morphometrics were not different between the groups but significantly greater tumor volume loss was seen even at 24 hours (-2.41 +/- 1.3 cm3 for the +GLN group vs -0.016 +/- 0.9 cm3 for the -GLN group). Tumor glutaminase activity was suppressed in both groups at 48 hours, but more so in the +GLN group (0.94 +/- 0.13 mumol/g per hour for the +GLN group vs 1.47 +/- 0.22 mumol/g per hour for the -GLN group). This study suggests that GLN may have therapeutic as well as nutritional benefit in oncology patients.

Total and free disopyramide by fluorescence polarization immunoassay and relationship between free fraction and alpha-1 acid glycoprotein.

Disopyramide is an antiarrhythmic drug with concentration dependent protein binding within the therapeutic range. We found good agreement between fluorescence polarization immunoassay (FPIA, Abbott TDX) and high performance liquid chromatography (HPLC) for total disopyramide among 27 admission patients' sera (FPIA = 1.12 (HPLC) -0.002, r = 0.982, SEE = 0.378 mg/l). Agreement between FPIA and HPLC for free disopyramide was similarly good (FPIA = 0.867 (HPLC) -0.003, r = 0.986, SEE = 0.09 mg/l, n = 27). Serum alpha 1 acid glycoprotein concentration (AAG) and free fraction (FF) percent of disopyramide correlated inversely (FF = -0.0112 (AAG) + 31.3 r = 0.707, SEE = 6.41 mg/l, n = 24), and the free disopyramide fraction varied greatly. For two pooled sera with 12 different disopyramide concentrations (range from 0.5-20.0 mg/l), the proportion of free fraction ranged from 6.5 to 73.2%. Overall, we found the free disopyramide fraction variable with each individual, total drug, and protein concentration. Therefore, free drug concentration should be monitored in disopyramide therapy, and FPIA is reliable for free as well as total drug assay.

The use of delta osmolality to predict serum isopropanol and acetone concentrations.

We investigated whether serum delta osmolality will predict the total serum concentration of isopropanol and acetone metabolite. Three isopropanol ingestions were monitored by delta osmolality determinations followed by quantification of serum isopropanol and acetone concentrations. The delta osmolality was established by routine chemical analysis and standard freezing point depression osmometry. Serum isopropanol and acetone levels were quantified by gas chromatography-head space analysis (GC-HS). Patients were initially suspected of having isopropanol intoxication secondary to an elevated delta osmolality discrepancy (measured - calculated > 10 mOsm). Serum concentrations versus delta osmolality were analyzed by linear regression (correlation coefficient r = 0.713; p < 0.05). The delta osmolality paralleled and decreased relative to the total low molecular weight of volatile concentration in each case. In emergencies, delta osmolality may be a screening test to identify rapidly patients at risk for complications associated with isopropanol ingestion when GC-HS is not available.

Vessel dilator is associated with survival after acute myocardial infarction.

To assess whether infarct size, ischemic area and/or survival correlates with circulating atrial natriuretic peptides (long acting sodium stimulator, vessel dilator, or atrial natriuretic factor), these peptides were measured in a canine model of acute myocardial infarction. Elevations in the circulating concentrations of atrial natriuretic factor, vessel dilator, and long acting sodium stimulator were significant (P < 0.05) within 6 min of coronary occlusion of the left anterior descending coronary artery. The percentage of ischemic myocardium ranged from 20 to 67% with a mean of 37 +/- 17%. The area of infarction ranged from 1 to 13% with the infarcted area of non-survivors being twice that of survivors. Both the ischemic and infarcted areas correlated (P < 0.05) with the circulating concentrations of these atrial natriuretic peptides. Survival correlated also with the circulating plasma concentrations of vessel dilator, atrial natriuretic factor and long acting sodium stimulator (P < 0.05). When these circulating concentrations were evaluated, however, by determining their area under their respective concentrations curves and expressing each as the log area under plasma concentration-time curve (area under the curve) per kg of weight (Y = 58.48X-23.62; r = 0.825; P = 0.0009), vessel dilator was the only atrial natriuretic peptide that correlated with survival.

Glutamine facilitates chemotherapy while reducing toxicity.

Dose intensification of chemotherapy is thought to increase survival. With recent advances in hemopoietic cell modulators such as granulocyte colony stimulating factor, the limiting toxicity of intensifying chemotherapeutic regimens has become the severity of the associated enterocolitis. In animal models, glutamine protects the host from methotrexate-induced enterocolitis. This study evaluates the effects of a glutamine-supplemented diet on the tumoricidal effectiveness of methotrexate. Sarcoma-bearing Fisher 344 rats (n = 30) were pair-fed an isocaloric elemental diet containing 1% glutamine or an isonitrogenous amount of glycine beginning on day 25 of the study. Rats from each group received two intraperitoneal injections of methotrexate (5 mg/kg) or saline on days 26 and 33 of the study. On day 40, rats were killed, tumor volume and weight were recorded, and tumor glutaminase activity and tumor morphometrics were measured. Blood was taken for arterial glutamine content, complete blood count, and blood culture. The gut was processed for glutaminase activity and synthesis phase of the deoxyribonucleic acid. In rats receiving methotrexate, the tumor volume loss was nearly doubled when glutamine was added to the diet. Significant differences in tumor glutaminase activity and morphometrics were not detected. The toxicity to the host was ameliorated. Significantly increased synthesis phase of deoxyribonucleic acid of the whole jejunum, decreased bacteremia, "sepsis," and mortality were demonstrated. Glutamine supplementation enhances the tumoricidal effectiveness of methotrexate while reducing its morbidity and mortality in this sarcoma rat model.

Prostatic acid phosphatase: clinical utility in detection, assessment, and monitoring carcinoma of the prostate.

Prostatic carcinoma is a significant cause of male cancer death. The majority of cases present as incurable disease. The measurement of acid phosphatase has served to confirm clinically suspected disease and staging. The immunochemical methods have increased clinical sensitivity and specificity in detecting curable occult or confined disease, but not significantly so as to warrant mass screening. Prostatic acid phosphatase remains a test for confirming clinical staging of prostatic carcinoma and a response factor to therapy at present.

Disopyramide: clinical indications, pharmacokinetics and laboratory assessment.

Disopyramide is an antiarrhythmic drug similar to quinidine and used primarily to treat ventricular ectopic systoles. Unlike quinidine which shows drug-drug interaction with digoxin, disopyramide appears to be free of this problem. Side effects include anticholinergic symptoms, cardiovascular problems, and some gastrointestinal discomfort. Disopyramide is metabolized to N-desisopropyl disopyramide in the liver with approximately 50 percent of the parent drug excreted unchanged. The elimination half-life varies from 4.5 to nine hours, and it can be even longer in cases of renal failure or myocardial infarction. There exists an extremely variable degree of protein binding (10 to 70 percent), which is highly dependent on concentration. The unbound (free) fraction increases with increasing drug concentration, making the interpretation of total disopyramide concentrations very difficult. Since the free drug concentration is more representative of availability to its receptor, and only the free fraction is available for renal excretion, the free drug concentration may represent a better predictor of therapeutic effectiveness. Methods for determining concentrations of disopyramide include gas chromatography, high performance liquid chromatography, homogeneous enzyme immunoassay (EMIT), and fluorescence polarization immunoassay. A method for performing both total and free disopyramide determinations is also described.

Laboratory identification of erythroblastosis fetalis.

The clinical laboratory assumes the paramount role of supplying accurate data to the attending physician for the diagnosis, treatment and prevention of HDN. Maternal prenatal testing identifies patients at risk for Rh-HDN. The antibody titer is of primary value in assessing patients as candidates for amniocentesis. Amniotic fluid analyses provide an assessment of fetal prognosis in HDN and also an assessment of gestational age, lung maturity, and placental function. In severe HDN, amniotic fluid analysis can indicate the need for intrauterine transfusion. Postnatal laboratory studies can confirm the suspected diagnosis of HDN, identify those neonates at risk of developing kernicturus, and provide the physician with information pertaining to the treatment of HDN. Finally, prenatal and postnatal laboratory testing identifies those females eligible for Rh-immune globulin therapy to prevent HDN in subsequent pregnancies.

Current status of radioligand antibodies in the treatment of malignancy.

Monoclonal anti-tumor antibodies labeled with a radioactive moiety present an exciting new approach to cancer therapy. With the advent of hybridoma technology, monoclonal antibodies can now be produced in quantity. Indeed, antibodies against tumor-related and tumor-specific antigens have been produced, labeled with a radioactive substance, and used therapeutically. The rationale for this therapeutic approach and the results of human clinical trials will be reported herein.

Rapid preparation of plasma for coagulation testing.

Currently recommended minimum centrifugation of whole blood to produce platelet-poor plasma for routine coagulation assays is 1000g relative centrifugal force for 10 minutes. Many clinical laboratories centrifuge blood for routine coagulation assays from 500g to 2000g, with spin times varying from 20 to 5 minutes. Ninety blood samples, routinely submitted to our coagulation laboratory, were prospectively assayed simultaneously for the prothrombin time, activated partial thromboplastin time, and fibrinogen level, comparing centrifugation at 11,000g for 2 minutes with centrifugation at 1000g for 10 minutes. Routine and readily available equipment and supplies were used. Platelet counts were performed on the supernatant plasma in each sample to determine the efficacy of platelet depletion. Excellent correlation of methods was observed for the prothrombin time, activated partial thromboplastin time, and fibrinogen level. Platelet counts on the plasma supernatant showed no significant difference between the two centrifugation methods. We concluded that high-speed centrifugation at 11,000g with a shortened spin time of 2 minutes and with the use of routinely available equipment and supplies can significantly decrease the specimen preparation time for routine coagulation testing.

Lymph node pathology of acquired immunodeficiency syndrome (AIDS).

There has been a recent notable increase in the number of patients in the United States seropositive for the human immunodeficiency virus (HIV) and also an increase in the number of otherwise healthy homosexuals with persistent generalized lymphadenopathy (PGL). Lymphoid tissue appears to be a favorite target for the initial viral infection, subsequent opportunistic infections, and associated neoplasms. Therefore, evaluation of PGL is important in understanding the nature of the disease. Biopsies of the acquired immunodeficiency syndrome (AIDS) lymph nodes show a spectrum of abnormal lymphoid proliferations, eventual lymphoid depletion, Kaposi's sarcoma, and malignant lymphoma. Although the individual features of AIDS-related lymphadenopathy may not be specific, the constellation of histologic, immunologic, ultrastructural, and fine needle aspiration findings is characteristic.

Reticulocyte counting by flow cytometry. A comparison with manual methods.

The reticulocyte count (RC) is a key diagnostic test in the evaluation, classification, and response to therapy of anemia. The RC, as determined by manual methods, has a frustrating inherent imprecision owing to its binomial counting statistics (i.e., low counts/low precision) and inaccuracy because of inter- and intraobserver variability as to what indeed is a reticulocyte. Fluorescent activated cytometric (FACS) analysis of reticulocytes by thiazole orange (TO) is a rapid, relatively simple, and precise method for counting reticulocytes. The automated method counts 10,000 cells or more vs. 1,000 cells counted by the manual method. Although inherently more precise, the FACS method may be inaccurate owing to the presence of Howell-Jolly bodies, nucleated red blood cells (RBCs), sickled cells, or giant platelets. The RC by FACS is well correlated with the manual method and the reference ranges are similar. A new parameter by FACS, the reticulocyte maturation index (RMI), provides an independent measurement of reticulocyte RNA content. Although the RMI does not correlate with RC either by FACS or manual methods, it does provide an independent parameter of erythropoietic activity and may be useful in predicting bone marrow engraftment or further subclassifying anemias. Determination by FACS of the RC offers significant advantages over manual methods in monitoring a patients erythropoietic response. However, one must be cognizant of potential pitfalls in the method.