Triamterene and renal stone formation

Area of Science:

• Nephrology
• Crystallography
• Materials Science

Background:

• Kidney stones, particularly calcium oxalate monohydrate (COM), are a significant health concern.
• The formation of COM crystals involves nucleation and growth processes in supersaturated urine.
• Triamterene (TA) is a diuretic used to treat hypertension and edema, and its role in stone formation is of interest.

Purpose of the Study:

• To investigate the influence of triamterene (TA) and its metabolites, parahydroxytriamterene (PHTA) and parahydroxytriamterene sulfate (PHTAS), on COM nucleation and crystal growth.
• To determine if TA and its metabolites can act as catalysts for COM precipitation.

Main Methods:

• Utilized a constant composition technique at 37°C with supersaturated solutions.
• Analyzed spontaneous precipitation of COM, measuring induction periods.
• Employed specific surface area analysis and scanning electron microscopy (SEM) to characterize crystal formation and seed material interaction.

Main Results:

• The addition of TA, PHTA, and PHTAS significantly reduced induction periods for COM precipitation.
• These triamterene-related compounds were found to act as heterogeneous nucleation sources for COM.
• The crystalline parahydroxytriamterene sulfate (PHTAS) specifically provided sites for well-formed COM crystal rosettes.

Conclusions:

• Triamterene (TA) and its metabolites (PHTA, PHTAS) catalyze the nucleation and growth of calcium oxalate monohydrate (COM) crystals.
• These findings suggest that TA and its metabolites may promote kidney stone formation.
• The study indicates a potential role for TA and its metabolites in catalyzing the precipitation of other stone-forming minerals in urine.