INTRODUCTIONReduced bone mineral density (BMD) is a common finding in calcium stone forming (SF) patients and experimental rats with idiopathic hypercalciuria (1–7). Epidemiologic studies have shown higher fracture rates in SF compared to control populations, particularly in males (8,9). The pathogenesis of decreased bone mass involves the interplay of many risk factor, some related to the diet (2), other concluded that negative calcium balance, produced by hypercalciuria and dietary restriction of calcium, could influence bone mass (1) and others (10,11) found impaired osteoblast activity without changes in the resorptive activity. Jaeger et al (12) found a negative correlation between pyridinoline in urine of 24 hours and tibial shaft BMD. Pacifici and Weisinger (13,14) believe that some cytokines may be responsible for increased bone resorption and loss of mineral content. Independent of the mechanisms that cause loss of bone mass, diverse treatments was use in the control of hypercalciuria. Some of them include different bisphosphonates (7,15), even though most consider the thiazide diuretics as the drug of choice (16-18). A few open-label prospective studies suggested that thiazide diuretics may have beneficial effects on bone (17). Two randomized studies (19,20) showed modest gains in bone mass. In the same way, in a prospective randomized placebo-controlled study a modest effect in preventing bone loss at the hip and spine was noted after 3 years (21).

OBJETIVETo evaluate the response to long-term use of thiazides as the only treatment in idiopathic hypercalciuria and nephrolithiasis and check the response of bone and bone remodeling markers

MATERIALS AND METHODSWe evaluated retrospectively bone mass and biochemical markers of bone remodeling in response to thiazide therapy in 48 consecutive renal stone formers with idiopathic hypercalciuria, 8 men, mean age 36.5 ± 14 years, weight 73.8 ±10 Kg, BMI 23.8 ± 3.5 Kg/m2 and 40 women, mean age 46.9 ± 11.5 years, weight 59.2 ± 9.9 Kg, BMI 23.4 ± 3.2 Kg/m2. The subjects were recruited, since 2003 to 2010, among the patients seen at the outpatient's clinic. Patients included in this report satisfied the following criteria: (a) all of them must have passed a urinary calculi or should have a positive detection study (either a plain abdominal radiograph or renal sonography), (b) all the patients showed normal renal function, (c) none had a diagnosis of primary hyperparathyroidism, intestinal fat malabsorption, distal renal tubular acidosis, systemic malignancy, or liver disease (cirrhosis or hepatitis), (d) no prior treatment with calcium, bisphosphonate, teriparatide, SERM, strontium ranelate, fluoride, or long-term glucocorticoid therapy (e) none had osteoporosis although there were 25 with the diagnosis of osteopenia (4 men and 21 women)

DENSITOMETRY MEASUREMENTSDual energy X-ray absorptiometry (DXA) measurements of lumbar spine (LS) and proximal femur (FN) were obtained at using instruments manufactured by Lunar Corporation (General Electric, Madison, WI, USA) or Hologic (Waltham,MA, USA). Bone densitometry as laboratory studies were performed at baselineand as far away as possible from the start of treatment

BIOCHEMICAL DETERMINATIONS Fasting morning venous blood samples where obtained before breakfast and analyzed for creatinine, calcium, phosphorus, 25 OH D, total alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BAP), glucose, total cholesterol, uric acid, serum potassium and C-telopeptide (CTX). 24-hour urine samples were obtained from each patient for determination of calcium, sodium and creatinine at baseline and during thiazide treatment corresponding as closely as possible to the last date of L2–L4 and femoral neck bone mineral density analysis. In 2-hour fasting urine sample was analyzed deoxypyridoline/creatinine (DPD).Serum and urine calcium, sodium and potassium were measured by ion-selective electrode (ISE) method using a Synchron CX3 automated analyzer (Beckman, Beckman Instruments inc., Brea, California, USA). Normal values for total serum calcium: 8.8-10.5 mg%. Creatinine (Jaffe) and phosphate (UV) were measured using CCX Spectrum automated analyzer (Abbott Labs, USA). Normal values for serum creatinine: females: 0.6 – 1.1 mg%; males 0.9 – 1.3 mg%; Normal values for phosphate: 2.7 - 4.5 mg%. Normal values for sodium Intact PTH was measured using Roche Elecsys PTH from Roche Diagnostics; normal values: 10-65 pg/ml. Sodium and potassium were measured by Synchron CX3 autoanalyzer. Uric acid Uric acid was analyzed by the uricase method. Total alkaline phosphatase and its bone isoenzyme (Kinetic method RR: 90-280 UI/l and 20-48% respectively). Deoxypyridoline (DPD) was measured by Elisa method (Metra Biosystems RR; normal values: females: 3-8 nM DPyr/mM Creat.and males: 2.3- 5.4 nM DPyr/mM Creat). We considered hypercalciuria a urinary calcium excretion > 220 mg/24 h for women and > 300 mg/24 h for men or > 4 mg/Kg body weight in both sexes on a normal calcium diet (~1000 mg/day). We also calculated the calcium/creatinine ratio in 24 hour urine both basal to the end of the study. We used the lowest possible dose of hydrochlorothiazide + amiloride which could control the calciuria, it ranged between 12.5 and 50 mg /d and 1.25 to 5 mg, respectively. We evaluated the response of calciuria, changes in bone mineral density in lumbar spine and femoral neck, bone remodeling markers and adverse effects of thiazides.

STATISTICSThe statistical significance of the differences between basal densitometry values and the following measurements was assessed by two-sided paired T-test. The same test was used for biochemical parameters, a p < 0.05 was considered significative.

RESULTSThe 48 patients with IH and nephrolithiasis were followed or 71.3 ± 48.0 months. Changes in urinary calcium, sodium and Ca / Kg are shown in Table I. The percentage increase of BMD was 2.38 % in lumbar spine and 1.4% in femoral neck Graphic I. Serum calcium, phosphorus and 25 OH D showed no significant changes between baseline and the end of the follow-up (9.7 ± 0.4 vs 9.8 ± 0.3, 3.6 ± 0.5 vs 3.4 ± 0.5 and 24 ± 14 vs 29 ± 8.5 respectively). The parameters of bone remodeling also did not change significantly in the average patient follow-up, Table 2. Of all patients, mild hypokalemia was observed in 39.4%, hyperglycemia in 7 (2 in the diabetic range, hypotension in 4, palpitations, cramps and headaches in 2 patients in each case. Cholesterol, uric acid and plasma sodium showed no changes in the follow up.

Table I: changes in urinary calcium, sodium and Ca / Kg basal and the end of follow-up

PROTECTIVE EFFECT OF THIAZIDES ON BONE MASS IN HYPERCALCIURIC NEPHROLITHIASIS

Instituto de Investigaciones Metabólicas, Universidad del Salvador, Buenos Aires, Argentina

Francisco R Spivacow, Armando L Negri, Elisa E del Valle

In all cases analysed the thiazides produced significant reduction in long-term calciuria. Bone densitometry showed a stability of their values and the mild adverse effects not caused suspension of medication in any case. It highlights the sustained efficacy of hydrochlorothiazide long-term effect on mineral metabolism in patients with idiopathic hypercaliuria and nephrolithiasis, especially in the control of hypercalciuria and maintaining long-term BMD.

Reference: 1. Zanchetta JR, Rodriguez G, Negri AL et al. Bone mineral density in patients with hypercalciuric nephrolithiasis. Nephron 1996; 73: 557–560. 2. Pietschmann F, Breslau NA, Pak CY. Reduced vertebral bone density in hypercalciuric nephrolithiasis. J Bone Miner Res 1992; 7: 1383–1388. 3. Weisinger JR: New insights into the pathogenesis of idiopathic hypercalciuria: The role of bone. Kidney Int 1996; 49: 1507-1518. 4. Giannini S, Nobile M, Sartori L et al. Bone density and skeletal metabolism are altered in idiopathic hypercalciuriaa. Clin Nephrol 1998; 50: 94–100. 5. Bataille P, Achard JM, Fournier A et al. Diet, vitamin D and vertebral mineral density in hypercalciuric calcium stone formers. Kidney Int 1991; 39: 1193–1205. 6. Borghi L, Meschi T, Guerra A et al. Vertebral mineral content indiet-dependent and diet-independent hypercalciuria. J Urol 1991; 146: 1334–1338. 7. Bushinsky DA, Neumann KJ, Asplin J, Krieger NS. Alendronate decreases urine calcium and supersaturation in genetic hypercalciuric rats. Kidney Int 1999: 55: 234-243. 8. Melton III LJ, Crowson CS, Khosla S et al. Fracture risk among patients with urolithiasis: a population-based cohort study. Kidney Int 1998; 53: 459–464. 9. Lauderdale DS, Thisted RA, Wen M, Favus MJ. Bone mineral density and fracture among prevalent kidney stone cases in the Third National Health and Nutrition Examination Survey. J Bone Miner Res 2001; 16: 1893–1898.10. Steiniche T, Christensen MS, Melsen F. A histomorphometry determination of iliac bone remodeling in patients with recurrent bone formation an idiopathic hypercalciuria. APMIS 97: 309-316, 1989. 11. Malluche HH, Tschoepe HH, Ritz WE, Massry SG: Abnormal bone histology in idiopathic hypercalciuria. J.Clin Endocrinol Metab 1980; 50: 654. 12. Jaeger P, Lippuner K, Hug C. Low Bone Mass in Idiopathic Renal Stone formers: Magnitude and Significance. J Bone Miner Res 1994; 9: 1525-32. 13. Weisinger JR, Alonzo E, Bellorin-Font E, Blasini AM, Rodríguez MA, Paz-Martinez V, Martinis R. Possibles role of cytokines on the bone mineral loss in idiopathic hypercalciuria. Kidney Int 1996; 49: 244-250. 14. Pacifici R, Rothstein M, Rifas L, Lau KW, Baylink D, Avioli LV, Hruska K. Increased monocyte interleukin-1 activity and decreases vertebral bone density in patients with fasting idiopathic hipercalciuria. J Clin Endocrinol Metab 1990; 71: 138-145. 15. Heilberg IP, Martini LA, Teixeira SH, Szejnfeld VL, Carvalho AB, Lobao R, Draibe SA. Effect of etidronate treatment on bone mass of male neprholithiasis patients with idipatic hypercalciuria and osteopenia. Neprhon 1998; 79: 430-437. 16. Rico H, Revilla M, Villa LF, Arribas I, Alvarez de Buergo M. A longitudinal study of total and regional bone mineral content and biochemical markers of bone resorption in patients wiht idiopatic hypercalciuria on thiazide treatment. Miner Electrolyte Metab 1993; 19: 337-342. 17. Legroux-Gerot I, Catanzariti L, Marchandise X, Duquesnoy B, Cortet B. Bone mineral density changes in hipercalciuretic osteoporotic men treated with thizide diuretics. Joint bone spine 2004; 71: 51-55. 18. Lalande A, Roux S, Denne MA, Stanley ER, Schiavi P, Guez D, De Vernejoul MC. Indapamide, a thiazide-like diuretic, decreases bone resorption in vitro. J bone Miner Res 2001; 16: 361-370. 19. Transbol I, Christensen MS, Jensen GF, Christiansen C, McNair P. Thiazide for the postponement of postmenopausal bone loss. Metabolism 1982; 31: 383-386. 20. Wasnich RD, Davis JW, He YF, Petrovich H, Ross PD. A randomized double-masked, placebo-controlled trial of chlorthalidone and bone loss in elderly women. Osteoporosis Int 1995; 5: 247-251. 21. La Croix AZ, Ott SM, Ichikawa I, Scholes D, Barlow WE. Low dose hydrochlorothiazide and preservation of bone mineral density in older adults. A randomized double-blind, placebo controlled trial. Ann Intern Med 2000; 133: 516-526.

IDIM - Instituto de Investigaciones Metabólicas www.idim.com.ar

months of follow-

up

Urine Basal (71.3 ± 48) p

Calcium

mg/24 h 306.53 ± 76.

4

195.7 ± 58.4 < 0.000

Ca / Kg 5.0 ± 1.1  3.24 ± 0.98 < 0.001

Sodium

mEq/24 h 162.59 ± 80 150.32 ± 62.8 NS

End of the follow-

upParamete

rs

Baseline P

ALP (UI/L) 162 ± 62 174 ± 62 NS

BAP (%) 46 ± 16.8 39 ± 12.7 NS

CTX

(pg/ml)

492 ± 265 403 ± 171 NS

1,047 1,072

0

0,2

0,4

0,6

0,8

1

1,2

gr/cm2

basal follow-up

Lumbar spine

0,855 0,867

0

0,2

0,4

0,6

0,8

1

gr/cm2

basal Follow-up

Femoral neck

Table 2: Bone remodeling markers in the 48patients with nephrolithiasis

Figure I: changes in basal BMD and the end of follow-up in lumbar spine and femoral neck