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Biomedical subjects

H G Tiselius

Publications and source records attributed to H G Tiselius.

At least 91 records · Page 5Linked to original sources
PubMed1987

The composition of four-hour urine samples from patients with calcium oxalate stone disease.

Urine collected during a 24-h period between 06.00 and 10.00 h from 25 patients with recurrent CaOx stone disease was analysed with respect to calcium, oxalate, magnesium, citrate and creatinine. Urinary excretion of oxalate in relation to creatinine was slightly higher in 24-h urine but the correlation between 24-h and 4-h values was good. Good correlations were also recorded for calcium and citrate, whereas a more variable result was obtained for magnesium. In terms of the risk of forming a supersaturated urine (CaOx risk index), a good correlation was observed between 24-h and 4-h urine samples, although the highest values were found in 24-h urine. As a result of a low mean urine flow between 06.00 and 10.00 h, the highest supersaturation in terms of the AP (CaOx) index was observed in these samples. When the risk of calcium oxalate crystallisation (CaOx-CR) was determined by means of the increment in oxalate concentration required for precipitation of CaOx, 7 of 11 samples had the highest values in the 4-h urine. Samples collected during a 4-h period might thus be useful in the evaluation and follow-up of CaOx stone formers and further studies will show to what extent they can replace 24-h urine collections.

Calcium↗
PubMed1987

Endocrine changes and urinary citrate excretion.

Urinary citrate affects the ion-activity products of calcium oxalate and calcium phosphate and inhibits the growth of these crystals. Women are less prone to develop calcium stones and because they also excrete more citrate than men, an effect of sex steroids on citrate excretion might be important. We therefore analysed urinary citrate and creatinine before and during treatment with estrogen alone or together with medroxyprogesterone acetate in 29 postmenopausal women and at different gestational ages in 19 pregnant women. Urinary citrate and creatinine was also determined before and after orchidectomy in ten men with carcinoma of the prostate. The excretion of citrate and the ratios between citrate and creatinine were not significantly altered by pregnancy or orchidectomy. Neither did treatment with estrogen or estrogen/medroxyprogesterone acetate affect these variables. We were unable to explain the difference in citrate excretion between men and women by effects of sex steroids.

Adult↗
PubMed1987

A method for description and classification of patients with urolithiasis.

A method for description and classification of patients with renal stone disease is presented. The system which has been used in the clinical routine during several years, summarizes information on the current stone situation, previous surgical procedures, the presence of anatomical abnormalities and the result of stone analysis. This system of classification provides a basis for surgical and medical decisions.

Humans↗
PubMed1987

Urine composition and stone formation during treatment with acetazolamide.

Twelve patients who formed renal stones during acetazolamide treatment for glaucoma were studied. Calcium phosphate was the dominating component in the stones. Long term treatment with acetazolamide decreased urinary citrate markedly, which will result in an increased ion-activity product of calcium phosphate and a decreased inhibiting property of urine on calcium phosphate crystallization. The treatment also increased urinary oxalate which together with a low citrate might increase the risk of calcium oxalate crystallization. However, an estimate of the ion-activity product of calcium oxalate in urine (AP [CaOx]-index) was unaffected by the treatment and calcium oxalate was a minor component of the stones.

Acetazolamide↗
PubMed1987

Hyperoxaluria.

Urinary oxalate is considered to play a crucial role in the formation of renal stones. In this respect hyperoxaluria constitutes a special problem, mainly because of the specific physicochemical properties of oxalate. The appropriate management of patients with this disorder must be based on a thorough understanding of the absorption, metabolism and excretion of oxalate. Different reasons for high oxalate excretion as well as analytical problems and our current therapeutic possibilities are covered in this review.

Humans↗
PubMed1986

Biochemical risk factors in patients with renal staghorn stone disease.

Thirty-three patients operated on for renal staghorn calculous disease were studied retrospectively with respect to urine and stone composition, bacteriuria, and abnormalities of the urinary tract. Calcium phosphate was the most common stone constituent, present in 30 of 31 concrements. Twenty-one of these stones also contained magnesium ammonium phosphate, despite the fact that only 10 patients had presented evidence of urinary tract infection during the initial period of the disease. Twenty-four-hour urine composition was normal in only 3 patients. In 59 per cent an increased CaOx risk index was observed suggesting that CaOx risk factors might contribute to the development of staghorn concrements. A metabolic evaluation of staghorn stone formers appears to be of importance for design of the postoperative treatment.

Adolescent↗
PubMed1986

Clinical results of allopurinol treatment in prevention of calcium oxalate stone formation.

Allopurinol in a daily dose of 300 mg. was administered to 99 patients with calcium oxalate stone disease. Treatment was started irrespective of urine composition and was continued for up to 8 years. Only 43 per cent of the patients treated for 5 or more years remained free of further stone formation, a result not better than observations in untreated stone patients. When patients were subgrouped with respect to recurrent or nonrecurrent stone formation during treatment, the former group, besides being followed for longer intervals than the latter group, had a urine composition suggesting a higher crystallization risk. We concluded that with the possible exception of hyperuricosuria or hyperuricemia the indication for allopurinol treatment of recurrent calcium oxalate stone disease is weak. The results also demonstrate clearly the problems combined with evaluation of prophylactic medical therapy in patients with calcium stones. The necessity of long-term followup and analysis of the biochemical risk situation is emphasized.

Allopurinol↗
PubMed1986

The effect of pH on the risk of calcium oxalate crystallization in urine.

The risk of calcium oxalate (CaOx) crystallization at different pH levels was determined in urine from recurrent CaOx-stone formers and normal subjects. The highest crystallization risk was observed between pH 4.5 and 5.5. In the pH range 6.5-7.5, there was a marked increase in crystallization of calcium phosphate (CaP). The results suggest the beneficial effect of moderate alkalinization in terms of a reduced CaOx crystallization. Reduced CaOx crystallization occurs at the expense of an increased formation of CaP crystals. Whether this increases the risk of CaP-stone formation is not known, but the CaP crystals were usually small, at least below pH 7.5.

Calcium↗
PubMed1986

An estimate of the ion-activity product of magnesium ammonium phosphate in urine.

Based on the analysis of magnesium (Mg), ammonium (NH4), phosphate (P), urine pH, and urine volume (V), a simplified estimate (AP[MAP] index) of the ion-activity product of magnesium ammonium phosphate (AP MAP) was derived: (Formula: see text). The factor A varies according to the collection period. In 4-hour urine samples more than half of the patients with staghorn calculi had values above 5 in contrast to normal subjects and calcium oxalate stone formers in whom lower values apparently were the rule. The AP(MAP) index might be of value in the evaluation and follow-up of patients with staghorn calculous disease.

Calcium Oxalate↗
PubMed1985

Measurement of the risk of calcium oxalate crystallization in urine.

The risk of calcium crystallization (CaOx-CR) in urine was analyzed by means of crystal counting following standardized addition of oxalate. CaOx-CR was determined in 24 h urine samples from 21 stone formers and 26 normal subjects following dilution of urine to a creatinine concentration of 5 mumol per ml. The mean (+/- SD) CaOx-CR was in stone formers 1.42 +/- 0.57 and in normal subjects 1.29 +/- 0.40. CaOx-CR was also analyzed in 16 fresh urine samples diluted to 80 per cent of the original concentration whereby values between 0.36 and 3.6 were recorded. There was a good correlation between CaOx-CR and estimates of the ion-activity product of CaOx, both in urine diluted to 5 mumol of creatinine per ml and in 80 per cent diluted urine. It ist suggested that the method described is of value for evaluation and follow up of patients with CaOx urolithiasis.

Calcium Oxalate↗
PubMed1984

A method for quantitative wet chemical analysis of urinary calculi.

We describe a simple method for quantitative chemical analysis of urinary calculi requiring no specialized equipment. Pulverized calculi are dried over silica gel at room temperature and dissolved in nitric acid, which was the only effective agent for complete dissolution. Calcium, magnesium, ammonium, and phosphate are then determined by conventional methods. Oxalate is determined by a method based on the quenching action of oxalate on the fluorescence of a zirconium-flavonol complex. Uric acid, when treated with nitric acid, is stoichiometrically converted to alloxan, which is determined fluorimetrically with 1,2-phenylenediamine. Similarly, cystine is oxidized by nitric acid to sulfate, which is determined turbidimetrically as barium sulfate. Protein is determined spectrophotometrically as xanthoprotein. The total mass recovery of authentic calculi was 92.2 +/- 6.7 (SD) per cent. The method permits analysis of calculi as small as 1.0 mg. Internal quality control is performed with specially designed control samples.

Cations↗
PubMed1984

Effects of sodium urate and uric acid crystals on the crystallization of calcium oxalate.

Crystallization of calcium oxalate in the presence of uric acid and sodium urate crystals was analyzed in a metastable crystallization system containing calcium chloride and sodium oxalate (A), in urine highly supersaturated with respect to calcium oxalate (B), and in urine with a high level of metastable supersaturation (C). In system A uric acid crystals in concentrations up to 11.4 mMol/l did not affect calcium oxalate crystallization, neither did sodium urate during the first 6 h in concentrations below 5 mMol/l. In system B neither uric acid nor sodium urate crystals affected calcium oxalate crystallization. However, an increased rate of crystallization was observed with both uric acid and sodium urate in system C, but the effect was less pronounced than with calcium oxalate seed. Urine pre-treated with sodium urate and subsequently analyzed in system A in a concentration of 2%, gave a slightly lower inhibition of calcium oxalate crystal growth. Concerning the crystal size distribution in the same system, larger crystals were observed in several urines pre-treated with uric acid and sodium urate.

Calcium Oxalate↗
PubMed1984

Studies on crystalluria in calcium oxalate stone formers.

The excretion of calcium oxalate and calcium phosphate crystals was studied in fractionated 24 h urine from 7 men with recurrent calcium oxalate stone disease, both before and during daily administration of 5 mg bendroflumethiazide. Urinary calcium, oxalate, magnesium, citrate, phosphate, pH, and inhibition of calcium oxalate crystal growth rate were analyzed in all samples. Exclusively calcium oxalate crystals were found in 30 per cent of the samples, all with a pH below 6.25, whereas calcium phosphate was the crystal type encountered in urine with a pH above 6.50. Bendroflumethiazide decreased the volume of calcium phosphate but not of calcium oxalate crystals. During the period of observation there was no correlation between calcium oxalate supersaturation and calcium oxalate crystal volume, but a relationship was demonstrated between calcium phosphate supersaturation and calcium phosphate crystal volume.

Adult↗
PubMed1984

Variations in urine composition during the day in patients with calcium oxalate stone disease.

The diurnal variations of urine composition with respect to calcium, magnesium, oxalate, citrate and inhibition of calcium oxalate crystal growth were studied in patients with recurrent calcium oxalate stone disease. There was considerable variation in the excretion of the different urine constituents with meal-related peaks, which was most pronounced for calcium. The highest concentration of calcium was observed before noon, and between 7 and 11 p.m. Oxalate concentration was highest between 6 and 10 a.m. Consequently, the highest levels of supersaturation were recorded between 6 and 10 a.m., and 6 and 10 p.m. The inhibition index was at the highest level during the first morning hours and could be important in counteracting crystal growth at that time. The risk of exceeding a theoretical formation product of calcium oxalate appeared to be low, with a 24-hour urine volume more than 2,000 ml.

Adult↗