Gravimetric determination of the water concentration in whole blood, plasma and erythrocytes and correlations with hematological and clinicochemical parameters.

We have assessed gravimetric methods for determination of intravascular water, established whole blood-, plasma- and erythrocyte water reference values in a healthy volunteer group (n = 97, 48 females) and correlated these variables with 30 simultaneous hematological, clinicochemical and body parameters. The water standard was 55.56 mol/kg = 100 mass %. For erythrocyte water determination three methods were evaluated: 2 indirect methods were easy to perform, the third, using a hematocrit centrifuge, was the most reliable. Imprecision (within-batch coefficient of variation (CV), %) was excellent: whole blood 0.2, plasma 0.1, erythrocytes 0.7-2.2 and recoveries (means, %) 99.7-100.1. Serum water was found to be slightly higher than plasma water. Volunteer group, mean reference values, mass %: whole blood water 79.7, plasma water 91.2, erythrocyte water, three methods 66.2, 64.6 and 64.2, respectively. Females had mean 1.6 mass % higher whole blood water and 0.9-1.0 mass % higher erythrocyte water than males with no difference in plasma water. In the volunteer group whole blood water correlated strongly with hematocrit (r = -0.96), hemoglobin (r = -0.94) and erythrocytes (r = -0.85) and centrifuge hematocrit (r = -0.91). Plasma water correlated strongly with plasma total protein (r = -0.74, all correlations P < 0.001). Hemoglobin and hematocrit can serve as surrogate parameters for whole blood water when water determination is not available; total protein reflects plasma water.

Whole blood and plasma water in health and disease: longitudinal and transverse observations and correlations with several different hematological and clinicochemical parameters.

In a healthy reference population, hemoglobin (Hgb) and hematocrit (Hct) have been proposed as surrogate markers for whole blood water (WBW). We have extended this study under different physiological and pathological conditions in two longitudinal series, viz. (1) acute hyper- and hypohydration experiments in a healthy individual and (2) three athletes running 5 km each, and in three transverse series, viz. (3) a young reference population (n = 97, 49 females), (4) an old reference population (n = 37, nine females) consisting of inhabitants of a nursing home and (5) cardiac, hematological and renal patients including severe anaemia, polycythaemia and abnormal protein levels (n = 50, 25 females) with suspected hydration disturbances. The only sex difference found was a lower WBW in males in the young reference group. The percentage change of PW was less than that of WBW. In all five groups together (n = 293) WBW correlated closely (P < 0.0001) with Hgb and Hct (both r = -0.95) and with erythrocyte count (r = -0.85), whereas PW correlated with total protein (Tprot) (r = -0.84). In the longitudinally studied groups (1) and (2) WBW also correlated (P < 0.0001) with cholesterol, Ca, Tprot, albumin, platelets, globulin and white blood cells (r +/- 0.98-0.37), while PW correlated (P < 0.0001) not only with the same clinicochemical parameters but also with Hct, Hgb and red blood cells (r +/- 0.98-0.44). The homeostasis of PW is more narrowly regulated than that of WBW. Hgb, Hct and erythrocyte count reflect WBW and Tprot reflects PW also under disease conditions. WBW (mass%) can be calculated from Hgb and Hct using the formulae: -0.09 x Hgb (g/l) + 91.7 and -28.6 x Hct (v/v) + 91.8 and PW (mass%) from Tprot using the formula: -0.09 x Tprot (g/l) + 97.6. Other correlations were observed only in a longitudinal setting and presumably are due to concentration and dilution.

Sjögren's syndrome and tear function parameters.

In a group of patients with keratoconjunctivitis sicca associated with Sjögren's syndrome, the Schirmer values were lower in the Sjögren group of patients in comparison with a comparable group in which KCS was not associated with any systemic disease and these differences reached almost statistical significance. But a significant decrease in tear fluid lactoferrin concentration and tear film break-up time was demonstrated. The combination of the tear fluid lactoferrin concentration, the Schirmer I test values and the tear film break-up time provides a basis for differential diagnosis that is of some value clinically. None of these parameters in itself appeared to be of any clinical value to differentiate between KCS patients who were or were not associated with Sjögren' syndrome.

The diagnostic power of the tests for tear gland related keratoconjunctivitis sicca.

Laboratory tear function tests, such as the lactoferrin and the lysozyme test, reflect the level of tear gland deficiency and are, therefore, very useful for the clinician in the diagnosis of keratoconjunctivitis sicca (KCS). Although these tests do have an excellent discriminatory ability, they should be used in addition to clinical tests, such as the Schirmer-1 test, the tear film break-up time (BUT) and the Rose bengal (Rb) staining test. Schirmer's test, the most commonly used clinical test, measures tear fluid production. The tear film BUT, on the other hand, is the only test which establishes tear film instability. The Rose bengal score is strongly related to secondary damage of the superficial epithelium of the cornea and conjunctiva in patients with KCS. Thus, combining the results of these various tests facilitates the diagnosis of KCS and also the differentiation between Sjögren's KCS and non-Sjögren's KCS.

Tear function parameters in keratoconjunctivitis sicca with and without the association of Sjögren's syndrome.

In a group of patients with keratoconjunctivitis sicca (KCS) associated with Sjögren's syndrome (SJ) a significant decrease in tear fluid lactoferrin concentration and tear film break-up time was demonstrated in comparison with a matched group in which KCS was not associated with any systemic disease. The Schirmer values were also lower in the SJ of patients and these differences almost reached statistical significance. None of these parameters in itself appeared to be of any clinical value to differentiate between KCS that was or was not associated with SJ. The combination of the tear fluid lactoferrin concentration, the Schirmer I test values and the tear film break-up time, however, provide a basis for differential diagnosis that is clinically of some value.