Hypercalcaemia and metabolic alkalosis with betel nut chewing: emphasis on its integrative pathophysiology.
BACKGROUND
Events in the gastrointestinal tract that might contribute to a high absorption of calcium were simulated in vitro to evaluate why only a small proportion of individuals who ingest alkaline calcium salts develop hypercalcaemia, hypokalaemia and metabolic alkalosis.


METHODS
A patient who chewed and swallowed around 40 betel nuts daily developed hypercalcaemia, metabolic alkalosis, hypokalaemia with renal potassium wasting, and renal insufficiency. The quantities of calcium and alkali per betel nut preparation were measured. Factors that might increase intestinal absorption of calcium were evaluated.


RESULTS
Hypercalcaemia in the index case was accompanied by a high daily calcium excretion (248 mg, 6.2 mmol). Circulating levels of 1,25-dihydroxyvitamin D(3) and parathyroid hormone were low. Hypokalaemia with a high transtubular K(+) concentration gradient, metabolic alkalosis, a low excretion of phosphate and a very low glomerular filtration rate were prominent features.


CONCLUSIONS
Possible explanations for the pathophysiology of metabolic alkalosis and hypokalaemia are provided. We speculate that a relatively greater availability of ionized calcium than inorganic phosphate in the lumen of the intestinal tract could have enhanced dietary calcium absorption.
Lin
Shih-Hua
SH
Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan. L521116@ndmc1.ndmctsgh.edu.tw
Lin
Yuh-Feng
YF
Cheema-Dhadli
Surinder
S
Davids
Mogamat Razeen
MR
Halperin
Mitchell L
ML
D000471:Alkalosis / Q000209:etiology* / Q000503:physiopathology*; D001114:Areca; D002021:Buffers; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000652:urine; D002119:Calcium Carbonate / Q000378:metabolism; D002130:Calcium Phosphates / Q000378:metabolism; D005919:Glomerular Filtration Rate; D006801:Humans; D006851:Hydrochloric Acid / Q000494:pharmacology; D006934:Hypercalcemia / Q000209:etiology* / Q000503:physiopathology*; D007008:Hypokalemia / Q000209:etiology; D007684:Kidney Tubules / Q000378:metabolism; D008297:Male; D008409:Mastication; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000652:urine; D011188:Potassium / Q000378:metabolism; D051437:Renal Insufficiency / Q000209:etiology
D002021:Buffers; D002130:Calcium Phosphates; D010281:Parathyroid Hormone; D010710:Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; D002117:Calcitriol; D002119:Calcium Carbonate; C485829:calcium phosphate, dibasic, anhydrous; D006851:Hydrochloric Acid; D011188:Potassium; D002118:Calcium