Editing Stones: Epidemiology and Pathogenesis (section)

=== Hyperoxaluria ===
* '''<span style="color:#ff0000">Classification (4):</span>'''
*# '''<span style="color:#ff0000">Primary hyperoxaluria</span>'''
*#* Due to '''rare autosomal recessive inherited disorders in glyoxylate metabolism''', '''leading to preferential oxidative conversion of glyoxylate to oxalate''', an end product of metabolism
*# '''<span style="color:#ff0000">Enteric hyperoxaluria</span>'''
*#* '''In patients with enteric hyperoxaluria, intestinal hyperabsorption of oxalate is the most significant risk factor leading to recurrent calculus formation'''
*#** '''<span style="color:#ff0000">Fat malabsorption results in increased intestinal oxalate absorption</span>'''
*#*** '''In fat malabsorption, saponification of fatty acids occurs with divalent cations such as calcium''' and magnesium, '''which reduces calcium available for complexation with oxalate''' thereby resulting in an increased amount of oxalate available for reabsorption.
*#*** '''The poorly absorbed fatty acids and bile salts may increase colonic permeability to oxalate, further enhancing intestinal oxalate absorption'''
*#*** '''<span style="color:#ff0000">Patients with enteric hyperoxaluria are more likely to form calcium oxalate stones,</span>''' due to increased urinary excretion of oxalate and decreased inhibitory activity from hypocitraturia, secondary to chronic metabolic acidosis and hypomagnesuria.
*#** '''<span style="color:#ff0000">Malabsorption of any cause (chronic diarrheal states, inflammatory bowel disease, celiac sprue, or intestinal resection)</span> can lead to increased intestinal absorption of oxalate and hyperoxaluria; as a result of intestinal fluid loss, patients will often exhibit dehydration, bicarbonate losses, low urine volume'''
*#*** '''Hyperoxaluria has been described in''' both stone-forming and non-stone-forming patients who have undergone '''Roux-en-Y gastric bypass surgery,''' with urinary oxalate levels in some patients exceeding 100 mg/day
*#**** '''<span style="color:#ff0000">Bariatric surgery patients typically develop enteric hyperoxaluria, which should be managed with calcium supplementation</span>'''
*#***** '''Iron deficiency is the most common cause of anemia following bariatric surgery,''' particularly in premenopausal women.
*#*** '''<span style="color:#ff0000">Chronic diarrheal syndromes</span> promote intestinal loss of alkali and dehydration, resulting in metabolic acidosis and reduced urinary citrate levels.'''
*#**** '''Chronic metabolic acidosis can lead to low urine pH, hypercalciuria, and hypocitraturia.'''
*#* '''Restricting oxalate is generally insufficient as the cause is not an overabundance of oxalate'''
*# '''<span style="color:#ff0000">Dietary hyperoxaluria</span>'''
*#* '''<span style="color:#ff0000">Overindulgence in oxalate-rich foods such as (Oxalate Rich Chocolate, Pepper, Nuts): Okra, Rhubarb, Chocolate, Pepper, Nuts, Tea (black), cocoa, spinach, mustard greens, pokeweed, swiss chard, beets, berries, wheat germ, and soy crackers can result in hyperoxaluria in otherwise normal individuals.</span>'''
*#** Compliance is difficult for regimens intending to eliminate all oxalate sources
*#* '''<span style="color:#ff0000">Severe calcium restriction may result in reduced intestinal binding of oxalate and increased intestinal oxalate absorption, hence calcium intake should be moderate, rather than restricted</span>'''
*#** '''<span style="color:#ff0000">Increasing calcium intake, which may include supplements, specifically timed with meals, may reduce hyperoxaluria</span>'''
*#* '''<span style="color:#ff0000">High substrate levels (vitamin C) can also cause hyperoxaluria;</span>''' doses should be limited to 2 g/day
*# '''<span style="color:#ff0000">Idiopathic hyperoxaluria</span>'''