Estimation of glomerular filtration rate with 99Tc(m)-DTPA: a comparative assessment of simplified methods.

In 40 adult patients undergoing gamma camera renography, glomerular filtration rate (GFR) was measured using simplified 99Tc(m)-DTPA methods (i.e. a personal modification of the 'slope' method which does not require dose calibration, Gates' method and Carlsen's method) and compared to reference results (obtained using Sapirstein's formula and Russell's two-sample method with 51Cr-EDTA). Estimation of GFR from plasma creatinine (the Cockroft-Gault formula) was also carried out. Bias and imprecision of the simplified estimates were determined by the Bland-Altman method. The GFR values of the 'slope' method correlated best with the reference values (R2 = 0.88, S.E.E. = 11.3 ml min[-1]). Correlation of the two methods based on external determination with the gamma camera was no better at estimating GFR than that from plasma creatinine. Moreover, Gates' method underestimated GFR at all levels between 25 and 150 ml min(-1), while Carlsen's method overestimated at low levels and underestimated at high levels. The bias was as follows (ml): Cockroft-Gault 2.4; 'slope' -4.1; Carlsen 7.5; Gates 16.7. The imprecision was as follows (ml): 'slope' 11.8; Cockroft-Gault 16.4; Carlsen 20.5; Gates 22.8. We conclude that our modification of the slope method correlated best with the reference results, and would appear suitable for routine practice because of the small error involved. When performing sequential renal scintigraphy, it can also be used for a quick check of dubious data based on gamma camera methods.

Determination of glomerular filtration rate with 99mTc-DTPA in clinical practice.

In order to assess the practical reliability of glomerular filtration rate (GFR) determination with 99mTc-DTPA and plasma sampling, the authors compared the results obtained with 51Cr-EDTA and 99mTc-DTPA in 50 patients using five easily applied methods (two double-plasma-sample methods and three single-plasma-sample methods), and two kits with different compositions. It was observed that: 1) there is no difference between the results obtained with the two different kits. 2) Compared with 51Cr-EDTA the 99mTc-DTPA overestimates the result by about 2 mL/min: precision is slightly lower with 99mTc-DTPA than with 51Cr-EDTA but is sufficient for practical use. 3) The method recommended by the authors on the basis of this experience is the Russell's method with two samples. 4) The simplified methods with one sample give comparable results to the Russell's method for GFR levels between 50 and 115 mL/min, while the results are unsatisfactory below 50 mL/min. 5) Among the single-sample methods, the authors suggest that of Christensen and Groth. 6) A preliminary estimate of GFR (from the serum creatinine level, for instance) is useful for the choice between double-plasma-sample methods and simplified methods. In conclusion, the authors consider that the estimation of GFR with 99mTc-DTPA can be performed efficiently in clinical practice even when operating in absolutely routine conditions.

The nightly spontaneous alkalinization of the stomach.

Authors evaluated eighty-four 24-hour intragastric pH recordings of 73 subjects in different pathophysiologic conditions. Among them there were 12 healthy subjects, 27 duodenal ulcer patients, 10 of whom were examined both before and after treatment with H2 receptor antagonists, 18 gastro-esophageal refluxers and 16 other patients who complained of dyspepsia of various origins. Authors observed a spontaneous nocturnal alkalinization phenomenon of the stomach (SNA) which began in the latter part of the night; its onset was strongly related with sleeping and interrupted by waking up. This phenomenon was absent in duodenal ulcer patients but could be restored by treatment with anti-H2 drugs. The authors, moreover, gave evidences of a relation between SNA and the vagal integrity and modulation of the gastric secretions.

Twenty-four-hour intragastric pH-metry: H2-receptor antagonist restoration of nightly gastric spontaneous alkalinization in duodenal ulcer healing.

Continuous 24-hour intragastric pH monitoring allows the evaluation of spontaneous late night gastric alkalinization phenomenon (SNA). This nocturnal increase of intragastric pH is strongly evident in healthy volunteers but is insignificant in patients with active duodenal ulcer. Gastric acidity was monitored by 24-hour continuous pH-metry in nine patients with active duodenal ulcer disease before and after two weeks of therapy with ranitidine. A twice daily dose of the drug (150 mg at 08.00 h and 150 mg at 20.00 h) was orally administered to each subject. Before treatment the ulcer patients did not show the SNA phenomenon, but the therapy led it to reappear. Ranitidine significantly reduced the time during which the gastric acidity was lower than 4 pH units; moreover the drug was effective on the ulcer healing during a period as brief as two weeks of therapy. At least a complete healing of the duodenal ulcer could be seen in patients whose overall gastric acidity time was reduced almost to the 40% of the pre-treatment value, meal times excluded from the pH-metric calculation.