“Both nTHP and pTHP can shift the zeta potential of calcium oxalate crystals towards more negative values; nTHP is significantly more potent than pTHP.”
“The size … nTHP and pTHP increases … calcium concentration or increasing ionic strength and with decreasing pH. The differences between nTHP and pTHP in surface charge and particle size … be based on differences in molecular structure and may cause functional differences in their ability to inhibit calcium oxalate crystal aggregation.”