Clinical significance of uric acid dihydrate in urinary stones.

15:11 EDT 3rd September 2015 | BioPortfolio

Summary of "Clinical significance of uric acid dihydrate in urinary stones."

Uric acid crystallizes as an anhydrous compound (UAA), a dihydrate (UAD) or a mixture of both. A monohydrate form is very rare. About 20% of uric acid stones contain a significant amount (≥20%) UAD. It is believed that UAD crystallizes under highly acidic conditions (urine pH ≤ 5.0). Up to now, metabolic data on patients with UAD stones have not been reported in the literature. One hundred and fifty patients with pure uric acid calculi were studied. Stone analysis was performed using X-ray diffraction. According to the stone analysis, they were divided in two groups: 1. UAD (≥20% UAD), 2. UAA (<20% UAD). In all patients the following parameters were examined: age, sex, number of recurrences, body mass index (BMI); blood: creatinine, uric acid, calcium, sodium, and potassium; urine: pH-profiles, volume, calcium, uric acid, citrate, ammonia, and urea. Group 1 (≥20% UAD) consisted of33patientsand group 2 (<20% UAD) of 117 patients. Between these groups, there was a significant difference concerning the number of recurrences, the urine volume, and the urinary excretion of calcium. Patients with ≥20% dihydrate had a mean BMI of 31.6 ± 7.5, a mean number of recurrences of 0.24 ± 0.44, an urine volume of 2.6 ± 0.8 l/24 h, and a calcium excretion of 4.5 ± 2.2 mmol/24 h, whereas those with <20% dihydrate had BMI of 29.9 ± 5.0, 1.10 ± 1.42 recurrences, urine volume of 2.3 ± 1.2 l/24 h, and calcium excretion of 3.2 ± 2.4 mmol/24 h. All the other parameters tested were not significantly different. For the first time, our study shows metabolic data in uric acid patients with a significant amount of UAD. The comparison between this group and those patients with <20% UAD revealed that the first group is less prone to develop recurrences. This is a relevant difference concerning the necessity of metaphylactic measures. We could not confirm in patients with dihydrate if the urinary pH is more acid than in those with insignificant amounts of dihydrate. The higher 24-h urine volume, the higher excretion of calcium, and the higher BMI in the UAD group may be of pathophysiological relevance and requires further attention.


Department of Urology and Paediatric Urology, regioMed Kliniken, Klinikum Coburg, Ketschendorfer Str. 33, 96450, Coburg, Germany,

Journal Details

This article was published in the following journal.

Name: Urological research
ISSN: 1434-0879


PubMed Articles [28252 Associated PubMed Articles listed on BioPortfolio]

Uric acid nephrolithiasis.

Nephrolithiasis is a common condition in the general population. About 5-10% of all kidney stones is composed of uric acid, however the prevalence of uric acid stones significantly increases among pat...

Kidney stone models for in vitro lithotripsy research: A Comprehensive Review.

Urinary lithiasis is a common disease with a lifetime risk of 12% in men and 5% in women1. The incidence of disease varies by age with peak occurrence between the ages of 20 and 40 years, sex with hig...

Serum uric acid levels and risk of developing preeclampsia.

It is well known that preeclampsia is associated to high uric acid levels, but the clinical assessment of this relationship is still under consideration. Our research was to evaluate if periodic doses...

Fructose and uric acid in diabetic nephropathy.

Clinical studies have reported associations between serum uric acid levels and the development of diabetic nephropathy, but the underlying mechanisms remain elusive. There is evidence from animal stud...

Serum uric acid concentrations and SLC2A9 genetic variation in Hispanic children: the Viva La Familia Study.

Elevated concentrations of serum uric acid are associated with increased risk of gout and renal and cardiovascular diseases. Genetic studies in adults have consistently identified associations of solu...

Clinical Trials [3421 Associated Clinical Trials listed on BioPortfolio]

Study of the Biological and Physical Manifestations of Spontaneous Uric Acid Kidney Stone Disease

This study has two aims: Aim 1: To determine the presence of accumulation of fat within cells and the functional consequences of this in the kidney by correlating kidney fat content with ...

Primary Prevention of Hypertension in Obese Adolescents

The purpose of this study is to examine the consequences of lowering serum uric acid in pre-hypertensive, obese adolescents pathways involved with how uric acid mediated hypertension and r...

Brushite Kidney Stones: A Registry and Database of Clinical and Laboratory Findings

Brushite kidney stones are a unique form of calcium phosphate stones that have a tendency to recur quickly if patients are not aggressively treated with stone prevention measures. Little r...

Effect of Urinary Alkalinization on Urine Uric Acid Precipitation and Crystallization in Adults With Type 1 Diabetes

The purpose of this study is to determine whether alkalinization of urine uric acid by 2 doses of sodium bicarbonate (1950mg) over 24-hours reduces precipitation and crystallization of uri...

Uric Acid and Long-term Outcomes in Chronic Kidney Disease

Patients in the earlier stages of Chronic kidney disease (CKD) are at risk both for the development of end-stage renal disease (ESRD) (define by the requirement for dialysis or kidney tran...

Medical and Biotech [MESH] Definitions

Low-density crystals or stones in any part of the URINARY TRACT. Their chemical compositions often include CALCIUM OXALATE, magnesium ammonium phosphate (struvite), CYSTINE, or URIC ACID.

Stones in the URINARY BLADDER; also known as vesical calculi, bladder stones, or cystoliths.

Formation of stones in any part of the URINARY TRACT, usually in the KIDNEY; URINARY BLADDER; or the URETER.

Agents that increase uric acid excretion by the kidney (URICOSURIC AGENTS), decrease uric acid production (antihyperuricemics), or alleviate the pain and inflammation of acute attacks of gout.

Excessive URIC ACID or urate in blood as defined by its solubility in plasma at 37 degrees C; greater than 0.42mmol per liter (7.0mg/dL) in men or 0.36mmol per liter (6.0mg/dL) in women. This condition is caused by overproduction of uric acid or impaired renal clearance. Hyperuricemia can be acquired, drug-induced or genetically determined (LESCH-NYHAN SYNDROME). It is associated with HYPERTENSION and GOUT.


Relevant Topics

Latest News Clinical Trials Research Drugs Reports Corporate
According to the National Arthritis Data Workgroup, an estimated 6 million people in the United States report having experienced gout at some point in their lives. In fact, gout is the most common form of inflammatory arthritis in men over the age of 40....

Latest News Clinical Trials Research Drugs Reports Corporate
Benign Prostatic Hyperplasia (BPH) Erectile Dysfunction Urology Urology is the branch of medicine concerned with the urinary tract and diseases that affect it. Examples include urethritis, urethrostenosis and incontinence. Urology is a su...

Latest News Clinical Trials Research Drugs Reports Corporate
Radiology is the branch of medicine that studies imaging of the body; X-ray (basic, angiography, barium swallows), ultrasound, MRI, CT and PET. These imaging techniques can be used to diagnose, but also to treat a range of conditions, by allowing visuali...