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Biomedical subjects

R K van Wermeskerken

Publications and source records attributed to R K van Wermeskerken.

9 recordsLinked to original sources
PubMed1998

Multicenter harmonization of common enzyme results by fresh patient-pool sera.

A region consisting of 19 clinical laboratories harmonized their calibration of seven common enzymes by using fresh patient-pool sera. One of the laboratories was chosen to act as Regional Reference Laboratory (RRL). This laboratory used internationally accepted (mostly IFCC) methods at 37 degrees C, with an intralaboratory CV < or = 2.5%. First, the reference ranges of the RRL were verified by analysis of a reference population and calculation of the results by a parametric method. Next, all laboratories, including the RRL, received six patient-pool sera and analyzed them at the same time on the same date. Enzyme calibration factors at each laboratory were converted on the basis of the slope, and occasionally the intercept, of regression analysis with the RRL and the individual laboratory. Before harmonization, the interlaboratory CVs varied from 16.9% to 61.6%. After harmonization, CVs decreased to between 5.0% and 9.5%. These results proved to be reproducible over a period of more than a year. Using internationally accepted inaccuracy and imprecision criteria, the achieved interlaboratory CVs permit the use of one set of reference ranges by all participating laboratories. Certified Reference Materials were analyzed, resulting in interlaboratory CVs as low as those achieved with patient-pool sera. These materials can act as commutable reference preparations, except for creatine kinase.

Alanine Transaminase↗
PubMed1991

Complexes of creatine kinase and immunoglobulins in serum identified by a nonimmune binding method.

We have developed a method for identifying IgG-complexed creatine kinase (CK; EC 2.7.3.2) (IgG-CK) and IgA-complexed CK (IgA-CK) in serum. We used immobilized Protein G to bind IgG-CK and immobilized jacalin to bind IgA-CK, leaving noncomplexed CK in solution. The noncomplexed CK and total CK were measured kinetically. The results are reported as CK bound to immobilized Protein G and CK bound to immobilized jacalin. We validated the method by using sera determined immunochemically to contain IgG-CK, IgA-CK, mitochondrial CK (CKmt), and free CK-BB. We demonstrated concomitant binding of CK and approximately 99% of IgG, and of CK and approximately 87% of IgA. For CK bound to immobilized Protein G and to immobilized jacalin, intra- and interassay precisions ranged from 2.5% to 9.6%, and detection limits were less than 9 318 U/L in 40 sera containing IgG-CK, and CK bound to immobilized jacalin ranged from 10 to 59 U/L in eight sera containing IgA-CK. These ranges represent the activities of immunoglobulin-bound CK in the sera. In 13 sera containing CKmt and in eight sera containing free CK-BB, the binding of CK was less than 9 U/L. Evidently, this method is useful for identifying IgG-CK and IgA-CK in serum.

Creatine Kinase↗
PubMed1990

Evaluation of microcytosis using serum ferritin and red blood cell distribution width.

Out of 104 patients with microcytosis (MCV less than 80 fl), 69% had an iron deficiency, 21% a chronic disease and 10% hemoglobinopathy or thalassemia trait. The absence of bone marrow iron stores or the response to iron supplementation were used to establish the diagnosis iron deficiency. On the basis of sensitivity (90%) and specificity (100%), the serum ferritin concentration is more suitable for assessment of iron deficiency than the serum iron concentration, the total iron-binding capacity or the percentual saturation of transferrin. The red cell distribution width (RDW) is the parameter with the highest sensitivity for iron deficiency (94%). An RDW value within the reference interval can be used to exclude iron deficiency in those cases in which the serum ferritin concentration does not accurately reflect the iron stores owing to severe tissue damage, as in inflammation or malignancy.

Adult↗
PubMed1981

The clinical significance of macrocytosis.

The cause of macrocytosis (mean corpuscular volume (MCV) greater than or equal to 105 fl) was investigated over a period of 16 months in the 70 known cases of +/- 4000 patients seen by the Department of Internal Medicine. By means of simple laboratory investigations the cause of elevated MCV was found in more than 90% of the cases. We found vitamin B12 or folic acid deficiency in 27 patients, alcohol abuse in 18, chronic persistent hepatitis in 2, hematological (pre-) malignancy in 9, hemolysis in 4, hypothyroidism in 2, and a drug effect in one patient. In 6 cases the elevated MCV could not be explained. Macrocytosis, a frequent finding that is not related to the hemoglobin concentration, is an indicator of serious pathology. The MCV level can be used to differentiate between the diagnostic categories. Only 21 patients (30%) had megaloblastic erythropoiesis that was difficult to recognize in the peripheral blood. Among the findings at routine laboratory investigations an elevated MCV may be the only indicator of vitamin deficiency, preleukemia or alcoholism.

Alcoholism↗