Tea is not recommended; plain boiled water is preferred.
From the standpoint of stone-forming mechanisms:
- Excessive excretion of stone-forming substances
Increased urinary calcium, oxalate or uric acid from prolonged immobilization, hyperthyroidism, idiopathic hypercalciuria, distal renal tubular acidosis, etc. - Low urine volume
Raises the concentration of salts and organic matrix. - Reduced urinary inhibitors of crystallization
Lower levels of citrate, pyrophosphate, magnesium, acidic glycosaminoglycans and trace elements. - Anatomical factors & infection
Urinary-tract obstruction causes stasis and local deposition; infection further promotes struvite or calcium-phosphate stones.
Uric-acid stones are linked to gout.
Oxalate metabolism
Oxalate is the second major component of calcium-oxalate stones, yet most patients have no inherited oxalate disorder.
Enteric hyperoxaluria (≈ 2 % of stone formers) arises from increased colonic absorption:
- In ileal disease, chronic pancreatitis or biliary disease, fat binds calcium, leaving free oxalate to be absorbed.
- Unabsorbed fatty acids and bile salts also increase mucosal permeability to oxalate.
- Absorptive hypercalciuria can secondarily raise oxalate uptake.
Because all of these mechanisms are aggravated by low urine output and additional oxalate intake, stone patients should drink plenty of plain water and avoid tea.
| Mechanism of stone formation | Key points | Practical implication |
|---|---|---|
| 1. ↑ Stone-forming solutes | Hyper-calciuria, -oxaluria or -uricosuria from immobilization, hyperthyroidism, idiopathic hypercalciuria, RTA, etc. | Dilute urine by drinking water; tea adds oxalate. |
| 2. ↓ Urine volume | Concentrated salts & matrix promote crystallization | High fluid intake (plain water) is essential. |
| 3. ↓ Crystallization inhibitors | Low citrate, Mg²⁺, pyrophosphate, GAGs, trace elements | Water maintains output; tea supplies no inhibitors. |
| 4. Obstruction + infection | Stasis + urease-producing bacteria → struvite/Ca-phosphate stones | Hydration reduces stasis; tea diuresis is mild & contains oxalate. |
| 5. Enteric hyperoxaluria | Fat-malabsorption (ileal disease, pancreatitis, biliary disease) leaves free oxalate for colonic uptake; tea oxalate worsens load | Avoid extra oxalate sources—tea, spinach, nuts. |
| Recommendation | Drink abundant plain boiled water; do not drink tea. |