Pre- and postoperative evaluation of renal function with five different tests in patients with primary hyperparathyroidism

Spectrum of renal dysfunction after curative parathyroidectomy in symptomatic primary hyperparathyroidism

OBJECTIVE

The long-term renal consequences of curative parathyroidectomy (PTX) in symptomatic primary hyperparathyroidism (sPHPT) are not well characterized. We aimed to assess renal glomerular and tubular functions in an sPHPT cohort at ≥1 year's follow-up.

DESIGN

Retrospective-prospective study.

METHODS

sPHPT patients with preoperative eGFR ≥60mL/min/1.73m² and in remission (normocalcemic) for ≥1 year after PTX underwent clinical and biochemical assessment (calcium profile, renal parameters). Ammonium chloride and bicarbonate loading tests were performed in patients with renal tubular dysfunction (RTD).

RESULTS

Forty-eight patients (31 females) with median plasma PTH 1,029 (338-1604) pg/mL and mean eGFR 109.2±26.0mL/min/1.73m² at diagnosis were evaluated at 5.62±3.66 years after curative PTX. At follow-up, eGFR was <60mL/min/m² in 5 patients (10.4%). Patients with >10% drop in eGFR (n=31) had significantly higher pre-PTX plasma PTH (1,137 vs. 687pg/mL), and longer time to post-PTX evaluation (6.8 vs. 3.4 years). RTD was seen in 11 patients (22.9%): urinary low molecular weight proteinuria (14.6%), distal renal tubular acidosis (12.5%), hypophosphatemia (8.3%), and hypokalemia (8.3%); RTD was associated with significantly lower post-PTX eGFR (72.7 vs. 95.4mL/min/m²). Five of the 7 RTD patients undergoing loading test had impaired urinary acidification, whereas none had impaired bicarbonate resorption.

CONCLUSIONS

Reduction in eGFR and subclinical RTD were prevalent at long-term follow-up in the present Asian-Indian cohort with cured sPHPT. Further studies are warranted to understand the clinical implications of these various renal abnormalities.

Effects of parathyroidectomy on kidney function in patients with primary hyperparathyroidism: Results of a prospective study

BACKGROUND

Altered glomerular filtration rate is a controversial indication for parathyroidectomy in patients with primary hyperparathyroidism. The objective of this study was to evaluate the estimated glomerular filtration rate change 12 months after parathyroidectomy for primary hyperparathyroidism according to preoperative kidney function.

METHOD

Patients who underwent parathyroidectomy for primary hyperparathyroidism between 2016 and 2021 (n = 381) were enrolled in a monocentric prospective cohort. Patients without 1-year follow-up or with missing data were excluded (n = 135, 35%). Patients were dichotomized according to their baseline estimated glomerular filtration rate: <60 mL/min (group 1) and ≥60 mL/min (group 2). Parameters were measured before and then at 6 and 12 months after parathyroidectomy.

RESULTS

Out of 246 included patients, 27 (11%) were assigned to group 1 and 219 (89%) to group 2. The mean baseline estimated glomerular filtration rate was 46.8 ± 11.5 and 87.3 ± 14.7 mL/min in groups 1 and 2, respectively. Group 1 patients were older (P = .0006) and had a higher median serum parathyroid hormone level (P = .021). At 6 months postoperative, 224 patients (91%) were normocalcemic. The estimated glomerular filtration rate raw change after parathyroidectomy was significantly higher in group 1 than in group 2 (4.2 ± 7.8 vs -2.2 ± 9.1 mL/min, P = .0004). In group 1, 13/27 patients (48%) improved their chronic kidney disease stage after parathyroidectomy, including 6/13 (46%) with postoperative estimated glomerular filtration rate ≥60 mL/min, whereas 2/27 (7%) worsened. The baseline estimated glomerular filtration rate <60 mL/min and elevated serum calcium level were associated with postoperative estimated glomerular filtration rate improvement in multivariable analysis (P = .0023 and .039, respectively).

CONCLUSION

Parathyroidectomy for primary hyperparathyroidism is more likely to improve kidney function in patients with preoperative estimated glomerular filtration rate <60 mL/min. These results strengthen the current guidelines for surgery.

Clinical features of sporadic multigland parathyroid disease

Background. Sporadic multigland parathyroid disease (MGD) account for 1/4 of all cases of primary hyperparathyroidism (PHPT). There are no specific signs of MGD in comparison with single-gland parathyroid disease in PHPT. The only radical treatment is surgical, therefore, determining the number of excessively functioning parathyroid glands at the preoperative stage is important for choosing the extent of the operation and the success of the treatment in general.The aim. To identify the specific signs of multigland parathyroid disease in patients who underwent surgery for primary hyperparathyroidism. Methods. We conducted a single-center prospective study including 126 cases of surgical treatment of PHPT from December 2019 to June 2021. The study included an analysis of demographic, clinical, laboratory parameters and visual methods of topical diagnosis of parathyroid glands (ultrasound, scintigraphy, multislice computed tomography). The main endpoint of the study was the identification of characteristic signs of MGD in patients with PHPT.Results. Lower values of creatinine (p ≤ 0.01; Mann – Whitney U-test), albuminadjusted calcium (p ≤ 0.05; Mann – Whitney U-test), parathyroid hormone (p ≤ 0.01; Mann – Whitney U-test), glomerular filtration rate (p ≤ 0.01; Mann – Whitney U-test) and inconsistency of two methods of preoperative imaging (p ≤ 0.01; χ2) were set as specific signs of multigland compared with single-gland parathyroid disease. Conclusion. The results of preoperative biochemical and imaging studies can become the basis for differentiating single-gland and multigland parathyroid disease in primary hyperparathyroidism.

The effect of parathyroidectomy compared to non-surgical surveillance on kidney function in primary hyperparathyroidism: a nationwide historic cohort study

BACKGROUND

Patients with primary hyperparathyroidism (pHPT) and impaired kidney function (estimated glomerular filtration rate (eGFR) < 60 mL/min) are offered parathyroidectomy (PTX) to protect them from further complications. Surprisingly, two recent uncontrolled cohort studies have suggested a further decrease in kidney function following PTX. We aimed to examine the effects of PTX compared to non-surgical surveillance on kidney function in pHPT patients.

METHODS

Historic cohort study. From the Danish National Patient Registry (NPR) and major medical biochemistry laboratories in Denmark, we identified 3585 patients with biochemically confirmed pHPT among whom n = 1977 (55%) were treated with PTX (PTX-group) whereas n = 1608 (45%) were followed without surgery (non-PTX group). Baseline was defined as time of diagnosis and kidney function was re-assessed 9-15 months after PTX (PTX group) or 9-15 months after diagnosis (non-PTX group).

RESULTS

At follow-up, eGFR had decreased significantly in the PTX- compared to the non-PTX-group (median - 4% vs. - 1%, p < 0.01). Stratification by baseline eGFR showed that the decrease was significant for those with a baseline eGFR value of 80-89 and > 90 mL/min, but not for those with lower eGFR values. Findings did not differ between patients with mild compared to moderate/severe hypercalcemia. However, after mutual adjustments, we identified baseline levels of calcium, PTH, and eGFR as well as age and treatment (PTX vs. no-PTX) as independent predictors for changes in kidney function.

CONCLUSION

Compared to non-surgical surveillance, PTX is associated with a small but significant decrease in kidney function in pHPT patients with an initial normal kidney function.

Independent effects of secondary hyperparathyroidism and hyperphosphatemia on chronic kidney disease progression and cardiovascular events: an analysis from the NEFRONA cohort

BACKGROUND

Secondary hyperparathyroidism (SHPT) is a complication of chronic kidney disease (CKD), and it is associated with changes in calcium and phosphate. These related changes have been associated with increased cardiovascular mortality and CKD progression. It is not clear whether negative outcomes linked to SHPT are confounded by such factors. The present study was designed to assess the possible independent effects of SHPT (defined as patients with excessive PTH levels or on treatment with PTH reducing agents) on the risk of CKD progression and CVE incidence in CKD patients, as well as whether hypercalcemia and/or hyperphosphatemia act as effect modifiers.

METHODS

The study enrolled 2445 CKD patients without previous CVE from the NEFRONA cohort (950 stage 3, 612 stage 4, 195 stage 5 and 688 on Dialysis). Multivariate logistic and Fine and Gray regression analysis were used to determine the risk of patients of suffering CKD progression or a CVE.

RESULTS

Prevalence of SHPT in the whole cohort was 65.6% (CKD 3 54.7%; CKD 4 74.7%; CKD 5 71.4%; Dialysis 68.6%). After 2-years, 301 patients presented CKD progression. During 4-years follow-up, 203 CVE were registered. Patients with SHPT showed a higher adjusted risk for CKD progression and CVE. Furthermore, hyperphosphatemia was shown to be an independent risk factor in both outcomes and did not modify SHPT effect. No significant interactions were detected between the presence of SHPT and hypercalcemia or hyperphosphatemia.

CONCLUSIONS

We conclude that SHPT and hyperphosphatemia are independently associated with CKD progression and the incidence of CVE in CKD patients.

Parathyroidectomy slows renal function decline in patients with primary hyperparathyroidism

PURPOSE

Primary hyperparathyroidism has deleterious effects on health and causes nephrolithiasis and osteoporosis. However, it remains unclear whether parathyroidectomy benefits kidney function among patients with primary hyperparathyroidism.

METHODS

In this retrospective study, patients with primary hyperparathyroidism receiving parathyroidectomy in a tertiary medical center between 2003 and 2017 were followed up until December 31 2017, death, or requiring renal replacement therapy. Impact of parathyroidectomy on kidney function was examined using longitudinal estimated glomerular filtration rate (eGFR) change scales: single, average, absolute difference, percent change, annual decline rate, and slope. We applied linear mixed-effect model to determine the effect of parathyroidectomy on kidney function.

RESULTS

During study period, 167 patients with primary hyperparathyroidism were identified from 498 parathyroidectomized patients, and finally, 27 patients fulfilled our stringent criteria. Median follow-up duration was 1.50 years (interquartile range 1.05-1.81) before surgery and 2.47 years (1.37-6.43) after surgery. Although parathyroidectomy did not affect amount of proteinuria and distribution of eGFR, parathyroidectomy significantly slowed decline rate of eGFR compared with that before surgery (- 1.67 versus - 2.73 mL/min/1.73 m²/year, p < 0.001). More importantly, parathyroidectomy made more beneficial effects on kidney function in patients with age < 65 years and those without chronic kidney disease or hypertension.

CONCLUSIONS

Our study showed that parathyroidectomy slows renal function decline irrespective of age or comorbidities, which offers novel insight into the revision of guidelines for surgical indications in primary hyperparathyroidism. Given small sample size, further large-scale controlled studies are warranted to confirm our findings.

A detailed appraisal of renal manifestations in primary hyperparathyroidism from Indian PHPT registry: Before and after curative parathyroidectomy

BACKGROUND

Primary hyperparathyroidism (PHPT) is a systemic disorder characterized by hypercalcaemia and inappropriately elevated parathyroid hormone (PTH). Renal manifestations are one of the main presenting features both in symptomatic and asymptomatic PHPT patients.

OBJECTIVES

We aimed to compare demographic, clinical and biochemical parameters of PHPT patients with and without renal manifestations and also analysed the influence of curative parathyroidectomy on renal functions.

METHODS

We retrospectively analysed the data of PHPT patients from the last 25 years (1995- March 2019) and compared the demographic and clinical presentation and biochemical measurements between patients with and without renal manifestations and evaluated the changes in renal functions after 1 year of curative parathyroidectomy.

RESULTS

Of the total 544 PHPT patients, 299 (55%) including 91 out of 141 (65%) males had renal manifestations. Among renal manifestations, nephrolithiasis and nephrocalcinosis were found in 41.7% and 27.6% PHPT patients, respectively. PHPT patients with renal manifestations had significantly higher creatinine (109.7 vs 79.6 µmol/L; P < .0001) and lower eGFR level (78.8 vs 93.9 mL/min/1.73 m² ; P < .0001) compared to patients without renal manifestations. Parathyroidectomy resolved the clinical symptoms with biochemical cure in the patients from both the groups. Patients with renal manifestations showed improvement in creatinine and eGFR levels after 1 year of curative parathyroidectomy; however, patients without renal manifestations showed no change in creatinine and eGFR levels.

CONCLUSION

Young age and male gender are predictors of renal manifestations in PHPT. Curative parathyroidectomy improves renal functions in PHPT patients with renal manifestations compared to PHPT patients without renal manifestation.

Acute and long-term kidney function after parathyroidectomy for primary hyperparathyroidism

Background

In kidney transplant patients, parathyroidectomy is associated with an acute decrease in renal function. Acute and chronic effects of parathyroidectomy on renal function have not been extensively studied in primary hyperparathyroidism (PHPT).

Methods

This retrospective cohort study included 494 patients undergoing parathyroidectomy for PHPT. Acute renal changes were evaluated daily until day 4 post-parathyroidectomy and were stratified according to acute kidney injury (AKI) criteria. Biochemical assessment included serum creatinine, total and ionized calcium, parathyroid hormone (PTH), and 25-hydroxyvitamin D (25OHD). The estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI equation. We compared preoperative and postoperative renal function up to 5 years of follow-up.

Results

A total of 391 (79.1%) patients were female, and 422 (85.4%) were non-African American. The median age was 58 years old. The median (first and third quartiles) preoperative serum creatinine, PTH and total calcium levels were 0.81 mg/dL (0.68–1.01), 154.5 pg/mL (106–238.5), and 10.9 mg/dL (10.3–11.5), respectively. The median (first and third quartiles) preoperative eGFR was 86 mL/min/1.73 m² (65–101.3). After surgery, the median acute decrease in the eGFR was 21 mL/min/1.73 m² (p<0.0001). Acutely, 41.1% of patients developed stage 1 AKI, 5.9% developed stage 2 AKI, and 1.8% developed stage 3 AKI. The acute eGFR decrease (%) was correlated with age and PTH, calcium and preoperative creatinine levels in univariate analysis. Multivariate analysis showed that the acute change was related to age and preoperative values of ionized calcium, phosphorus and creatinine. The change at 12 months was related to sex, preoperative creatinine and 25OHD. Permanent reduction in the eGFR occurred in 60.7% of patients after an acute episode.

Conclusion

There was significant acute impairment in renal function after parathyroidectomy for PHPT, and almost half of the patients met the criteria for AKI. Significant eGFR recovery was observed during the first month after surgery, but a small permanent reduction may occur. Patients treated for PHPT seemed to present with prominent renal dysfunction compared to patients who underwent thyroidectomy.

Effects of preoperative calcium levels and parathyroidectomy on renal function in primary hyperparathyroidism: a retrospective study

AIM

TTo assess the effects of preoperative calcium levels and parathyroidectomy on estimated glomerular filtration rate (eGFR) in patients of primary hyperparathyroidism (PHPT) with mild renal dysfunction or normal renal function.

METHODS

This retrospective study enrolled 71 patients who underwent parathyroidectomy for PHPT in the General Surgery Department at Ondokuz Mayis University Hospital from 2010 to 2018. All patients were histopathologically diagnosed with parathyroid adenoma. Total serum calcium, serum creatinine, serum intact parathyroid hormone (PTH), and serum 25-hydroxyvitamin D3 (25(OH)D3) were measured before and 3-6 months after surgery. Patients were assigned to the low eGFR group (60-90 mL/min/1.73 m2) or normal eGFR group (≥90 mL/min/1.73 m2) and to the low calcium group (≤11.2 mg/dL) or high calcium group (>11.2 mg/dL).

RESULTS

In the low eGFR and high calcium group, there were significantly more patients with hypertension and older age. In the normal eGFR and high calcium group, eGFR was significantly reduced after surgery. Independent predictors of eGFR change after surgery were age, pre- parathyroidectomy calcium, and pre-parathyroidectomy eGFR.

CONCLUSIONS

After surgery, patients with low eGFR had preserved renal function, whereas those with normal eGFR had decreased renal function. Mild renal dysfunction in PHPT was associated with older age, hypertension, and high calcium levels.

Factors associated with glomerular filtration rate variation in primary hyperparathyroidism after parathyroidectomy

Background/aim

Prolonged hypercalcemia impairs renal function, and a reduced glomerular filtration rate (GFR) is typical in advanced primary hyperparathyroidism (PHPT). There are scarce data related to predictors of renal impairment in patients with PHPT. Hence, we aimed to evaluate changes in kidney function in PHPT patients after parathyroidectomy (PTX) and identify factors associated with GFR variation in these patients.

Materials and methods

One hundred and twenty-five patients with PHPT who underwent surgery between 2012 and 2014 were enrolled in the study. Patients were divided into two groups according to GFR values: patients whose GFR was lower than 60 mL/min/1.73 m2 and higher than 60 mL/min/1.73 m2. Demographic and laboratory parameters were compared before and 6 months after parathyroidectomy.

Results

Prevalence of antihypertensive drug users and patients with renal cysts and parathormone (PTH) and alkaline phosphatase levels were higher in patients with GFR of ≥60 than in GFR of <60 mL/min/1.73 m2 (P < 0.05). Systolic BP, uric acid, and magnesium were decreased in patients with GFR of ≥60, but GFR did not change in the two groups after parathyroidectomy. After parathyroidectomy, calcium and PTH decreased but 25(OH)D3 and phosphorus increased in the two groups. In multiple regression analysis, age, calcium, and baseline GFR were independent predictors of GFR variation. Parathyroid adenoma volume and urinary calcium were not independent predictors of GFR change.

Conclusion

Older age, higher preoperative calcium, and GFR were factors associated with GFR increase in PHPT patients after parathyroidectomy. Further renal impairment was prevented by parathyroidectomy in PHPT patients.

Primary hyperparathyroidism

In this Review, we describe the pathogenesis, diagnosis and management of primary hyperparathyroidism (PHPT), with a focus on recent advances in the field. PHPT is a common endocrine disorder that is characterized by hypercalcaemia and elevated or inappropriately normal serum levels of parathyroid hormone. Most often, the presentation of PHPT is asymptomatic in regions of the world where serum levels of calcium are routinely measured. In addition to mild hypercalcaemia, PHPT can manifest with osteoporosis and hypercalciuria as well as with vertebral fractures and nephrolithiasis, both of which can be asymptomatic. Other clinical forms of PHPT, such as classical disease and normocalcaemic PHPT, are less common. Parathyroidectomy, the only curative treatment for PHPT, is recommended in patients with symptoms and those with asymptomatic disease who are at risk of progression or have subclinical evidence of end-organ sequelae. Parathyroidectomy results in an increase in BMD and a reduction in nephrolithiasis. Various medical therapies can increase BMD or reduce serum levels of calcium, but no single drug can do both. More data are needed regarding the neuropsychological manifestations of PHPT and the pathogenetic mechanisms leading to sporadic PHPT, as well as on risk factors for complications of the disorder. Future work that advances our knowledge in these areas will improve the management of the disorder.

MECHANISMS IN ENDOCRINOLOGY: Kidney involvement in patients with primary hyperparathyroidism: an update on clinical and molecular aspects

Primary hyperparathyroidism (PHPT) is the third most common endocrine disease. Kidney is a target of both chronic elevated PTH and calcium in PHPT. The classic PHPT complications of symptomatic kidney stones and nephrocalcinosis have become rare and the PHPT current presentation is asymptomatic with uncertain and long-lasting progression. Nonetheless, the routine use of imaging and of biochemical determinations have revealed the frequent occurrence of asymptomatic kidney stones, hypercalciuria and reduced kidney function in asymptomatic PHPT patients. Though the pathogenesis is far from being elucidated, PHPT is associated with reduced renal function, in terms of estimated glomerular filtration rate, and related increased morbidity and mortality. In the last decade, the effort of the Kidney Disease: Improving Global Outcomes (KDIGO) panel of experts highlighted that even mild reduction of kidney function is associated with increased risk of cardiovascular disease. These considerations provided the basis for the Fourth Workshop recommendations of a more extensive diagnostic workout about kidney features and of wider criteria for parathyroid surgery including asymptomatic kidney disease. Moreover, kidney involvement in PHPT is likely to be affected by variants of genes coding the key molecules regulating the calcium and ions renal handling; these features might have clinical relevance and should be considered both during diagnostic workout and follow-up. Finally, the effects of parathyroid surgery and of medical treatment on kidney involvement of PHPT are reviewed.

Surgery or no surgery: What works best for the kidneys in primary hyperparathyroidism? A study in a multi-ethnic Asian population

INTRODUCTION

Whether parathyroidectomy is more beneficial to renal function when compared to medical therapy or observation in primary hyperparathyroidism (PHPT) is unclear. Neither has this premise been explored in non-Caucasian populations. The estimated glomerular filtration rate (eGFR) threshold below which parathyroid hormone (PTH) levels rise if at all in PHPT has also not been established. We determined if surgery was superior to medical therapy and observation in a multi-ethnic Asian patient population with PHPT and whether there was an eGFR threshold below which PTH levels further increased in them.

METHODS

Retrospective evaluation of patients with PHPT.

RESULTS

There were 68.6% Chinese, 17.4% Malays, 10.7% Indians, and 3.3% Eurasians. The median (interquartile range) follow-up was 18.0 months (4.5-46.8). At last follow-up, eGFR in the surgical (80 ± 30 ml/min) was higher than the medical (52 ± 32 ml/min) or observation groups (48 ± 33 ml/min); P < 0.01. This difference persisted after adjusting for age, gender, ethnicity, pre-intervention eGFR levels, nephrolithiasis, serum calcium, phosphate, urinary calcium, and duration of follow-up; P = 0.035. There was no definite eGFR level below which PTH values rose.

CONCLUSION

Our study provides compelling evidence that in PHPT, surgery may be associated with a better renal outcome compared to medical management or observation. This has to be confirmed through prospective randomized controlled trials and the reasons for this finding have to be elucidated through functional and histological measures. The finding in our study of a lack of a specific eGFR threshold below which PTH levels further rose challenges the concept of a fixed renal threshold for secondary elevations of PTH in PHPT.

Renal impairment as a surgical indication in primary hyperparathyroidism: do the data support this recommendation?

CONTENT

Management of primary hyperparathyroidism has evolved over the past two decades, yet impaired renal function has consistently been a surgical indication. This recommendation has been based upon the historical association between primary hyperparathyroidism and renal impairment, and a review of the literature is needed to determine whether such a recommendation is warranted.

EVIDENCE ACQUISITION AND SYNTHESIS

PubMed was utilized to identify English-language articles published between January 1990 and February 2014 using keywords related to hyperparathyroidism and renal function. The keywords were "primary hyperparathyroidism," "surgery," "parathyroidectomy," "kidney," "renal," "glomerular filtration rate," and "creatinine." Of the 1926 articles obtained with this search, all articles germane to the topic that quantified the relationship between primary hyperparathyroidism and renal function were included. All references within these articles were investigated for inclusion. When helpful, data tables were constructed to summarize the results succinctly.

CONCLUSIONS

A secondary elevation of PTH levels has not been consistently shown to occur at the threshold currently indicated for surgical intervention. While renal impairment is seen with more significant disease, mild asymptomatic primary hyperparathyroidism has not been conclusively associated with renal impairment. Furthermore, there is no evidence to suggest that surgically curing primary hyperparathyroidism via a parathyroidectomy has any impact upon renal function.

Predictors of renal function in primary hyperparathyroidism

CONTEXT

Current guidelines for parathyroidectomy in primary hyperparathyroidism (PHPT) include an estimated glomerular filtration rate (eGFR) less than 60 mL/min per 1.73 m(2). Although the biochemical abnormalities associated with PHPT could impair renal function, there are currently no data examining whether more severe hypercalcemia, hypercalciuria, or nephrolithiasis are associated with chronic kidney disease (CKD) in mild PHPT.

OBJECTIVE

This cross-sectional study evaluated predictors of renal function in PHPT.

DESIGN

This is a case series of PHPT patients with (eGFR < 60 mL/min per 1.73 m(2)) and without (eGFR ≥ 60 mL/min per 1.73 m(2)) CKD.

SETTINGS AND PARTICIPANTS

We studied 114 PHPT patients in a university hospital setting.

OUTCOME MEASURES

We identified predictors of renal function using multiple linear regression.

RESULTS

eGFR was associated with age, hypertension, antihypertensive medication use, fasting glucose, and 25-hydroxyvitamin D. eGFR was positively rather than negatively associated with several PHPT disease severity indices including history of nephrolithiasis, 24-hour urinary calcium excretion, and 1,25-dihydroxyvitamin D but not serum calcium or PTH levels. An eGFR less than 60 mL/min per 1.73 m(2) was observed in 15% (n = 17), all of whom had stage 3 CKD (eGFR 30-59 mL/min per 1.73 m(2)). Those with CKD were older, had higher 25-hydroxyvitamin D levels and lower 1,25-dihydroxyvitamin D levels, and were more likely to be hypertensive than those without CKD. There were no between-group (<60 vs ≥60 mL/min per 1.73 m(2)) differences in serum calcium, PTH, nephrolithiasis, or meeting surgical criteria other than eGFR. Multiple linear regression indicated that age and diastolic blood pressure were negatively associated with eGFR, whereas serum calcium, kidney stones, and alcohol use were positive predictors. Calculation of eGFR using either the Modification of Diet in Renal Disease or Chronic Kidney Disease Epidemiology Collaboration equation yielded similar results.

CONCLUSIONS

PHPT patients with stage 3 CKD do not have biochemical or clinical evidence of more severe hyperparathyroidism compared with those without CKD. Traditional risk factors, rather than clinical or biochemical indices of PHPT, are associated with lower eGFR in mild PHPT.

Unmasked renal impairment and prolonged hyperkalemia after unilateral adrenalectomy for primary aldosteronism coexisting with primary hyperparathyroidism: report of a case

We herein report the case of a patient with critical hyperkalemia after unilateral adrenalectomy (ADX) for aldosterone-producing adenomas, which were coexisting with primary hyperparathyroidism. A right adrenal tumor oversecreting mineral corticoid was identified in a 62-year-old female whose kidney function had been impaired due to primary hyperaldosteronism and hyperparathyroidism. The ADX improved her hypertension with normalization of the plasma aldosterone concentration, but without adequately increasing her plasma renin activity. Her eGFR further decreased postoperatively, hyperkalemia appeared and the serum potassium level rose to 6.3 mEq/L at 3 months after ADX. Then, treatment with calcium polystyrene sulfonate jelly was started. Eight months after ADX, a left lower parathyroidectomy was performed, and the serum calcium and intact parathyroid hormone levels decreased to the normal range. The hyperkalemia was difficult to control within 20 months postoperatively without treatment with calcium polystyrene sulfonate jelly or hydrocortisone. This suggests that unmasking the renal impairment and relative hypoaldosteronism after ADX might induce critical hyperkalemia.

Prospective evaluation of symptom responses to successful operation for mild-moderate primary hyperparathyroidism

BACKGROUND

Parathyroidectomy is claimed to strongly improve the hypercalcemic symptoms in patients with primary hyperparathyroidism (HPT). The object of this study was to register the patients own experience of symptom changes in response to successful parathyroid surgery.

METHODS

Material one. 44 HPT patients filled in a questionnaire consisting of 8 visual analogue scales referring to "typical" hypercalcemic symptoms before as well as 2 and 12 months after neck surgery. Their results were compared with those obtained from an age- and sex-matched group of patients undergoing surgery for non-toxic thyroid disease. Material two. 25 elderly women with mild-moderate HPT were followed more closely up to 3 years after neck surgery with the same type of questionnaire.

RESULTS

HPT patients expressed significantly more of fatigue, muscular weakness, impaired memory, thirst and polyuria than patients with non-toxic thyroid disorders. These differences were eliminated 2 months after surgery. The pattern of response to parathyroidectomy was similar for most symptoms: an impressive improvement after 2 months and then a gradual return towards the preoperative value. However, the response was still significant for fatigue, weakness, thirst, polyuria and inactivity after 1 year. The effect of normalization of serum calcium on symptom scoring varied considerably between different individuals and also between different symptoms in the same individual. The elderly women responded in a similar biphasic way but their improvements were less pronounced.

CONCLUSIONS

HPT patients experience significant improvements of most "hypercalcemic" symtoms after successful parathyroidectomy, but the effects are transient and vary considerably between different individuals.

Reelevation of parathyroid hormone level after parathyroidectomy in patients with primary hyperparathyroidism: importance of decreased renal parathyroid hormone sensitivity

BACKGROUND

We hypothesized that impaired peripheral sensitivity to parathyroid hormone (PTH) may play a role in reelevation of PTH after successful operation for primary hyperparathyroidism (pHPT).

METHODS

Factors affecting reelevation of PTH were determined in 90 patients who underwent parathyroidectomy for pHPT. PTH/nephrogenous cyclic adenosine monophosphate ratio, as an index of renal resistance to PTH, was examined in relation to factors shown to influence reelevation of PTH.

RESULTS

Serum PTH levels were elevated above the upper limit of normal in 23 patients (26%) at 1 week and in 39 patients (43%) at 1 month after parathyroidectomy. These 39 normocalcemic patients with elevated serum PTH at 1 month after parathyroidectomy had a higher preoperative serum level of PTH and lower serum phosphate and 25-hydroxyvitamin D (25OHD) concentrations than those with normal PTH (n = 59). Elevated PTH and low 25OHD were shown by multivariate analysis to be significant predictors of reelevation of PTH. Renal resistance to PTH was higher in patients with vitamin D deficiency or renal insufficiency than in patients with normal serum vitamin D concentrations or normal renal function, and it increased according to increases in levels of PTH.

CONCLUSIONS

The mechanism of PTH reelevation in patients with pHPT after successful parathyroidectomy appears to be renal resistance to PTH.

Risk factors associated to kidney stones in primary hyperparathyroidism

Nephrolithiasis is the most important clinical manifestation of primary hyperparathyroidism (PHPT), although nowadays this disorder is often asymptomatic. Clinical or biochemical differences between PHPT patients with and without nephrolithiasis have not been clearly identified in most of the previous studies. The aim of the study was to investigate clinical and biochemical parameters in kidney stone former (SF) and non-stone former (NSF) patients with PHPT in order to identify potential risk factors. Serum and plasma samples from 55 consecutive patients (43 females, 12 males) with PHPT were collected after overnight fasting; 24-h urine collection and a fresh sample of urine for sediment analysis were obtained from all patients. Clinical data were recorded in all. Out of 55 patients, 22 had kidney stones, which were symptomatic in 73%. SFs showed circulating PTH, total and ionized calcium, 1,25 dihydroxyvitamin D3, urinary calcium excretion and 24-h urine oxalate levels significantly higher than NSFs. Hypercalciuria was often concomitant with massive quantities of calcium oxalate crystals in urine sediment. Hypercalciuria and relatively high oxaluria were associated with stone formation with an odds ratio (OR) of 4.0 and 7.0, respectively, which rose to 33.5 when they coexisted. Hypomagnesuria and hypocitraturia were common in at least one third of all PHPT patients, but they were not associated to an increased OR. As expected, they were positively correlated with urine calcium excretion, suggesting that calcium, magnesium and citrate are commonly regulated at renal level. In conclusion, hypercalciuria, higher oxalate excretion and severe PHPT are associated with kidney stones in PHPT.

Urate and arteriosclerosis in primary hyperparathyroidism

OBJECTIVE

An increased mortality due to cardiovascular disease has been reported in patients with primary hyperparathyroidism (pHPT). An association between urate and cardiovascular disease has been suggested. Metabolic abnormalities in pHPT may include urate. We therefore evaluated the metabolic arteriosclerotic risk profile in pHPT with special focus on the role of urate.

DESIGN

Retrospective analysis of data before and 1 year after surgery for pHPT.

PATIENTS

130 consecutive patients, over the age of 44 years, who underwent surgery for pHPT.

MEASUREMENTS

Biochemical variables known to reflect risk of arteriosclerotic disease (AD) and renal function tests including measurement of glomerular filtration rate (GFR) were investigated before and 1 year after surgery.

RESULTS

pHPT patients with AD (n = 40) were older and had higher serum levels of urate and triglyceride, and more impaired renal function in comparison with patients without AD. PTH and calcium values did not differ. Multiple logistic regression analysis indicated that urate was an independent risk factor for AD in pHPT (P < 0.01). Three variables were shown to be positively associated with urate; male gender (P < 0.01), fasting blood glucose (P < 0.05) and serum level of triglyceride (P < 0.05).

CONCLUSIONS

Urate was found to be an independent risk factor for arteriosclerotic disease in primary hyperparathyroidism. Serum level of urate could (in addition to gender) be associated with a metabolic disorder comprising increased glucose and triglyceride levels.

Changes in renal hemodynamics and tubular function of surgically cured primary hyperparathyroid patients are probably due to chronic hypercalcemic nephropathy

To understand the mechanisms responsible for the persistent hypercalciuria and reduced glomerular filtration rate (GFR) previously found in 6 of 10 patients surgically cured of primary hyperparathyroidism (PHPx), the tubular handling of lithium, sodium, calcium, and phosphate as well as the renal hemodynamics were evaluated in these 10 PHPx patients, in 10 control subjects, and in 5 patients with renal hypercalciuria (RH), during fasting and after an oral calcium load. A positive correlation between the fractional excretions of calcium and sodium was found in all groups, but the PHPx patients excreted more calcium for the same amount of sodium than control subjects. The fractional proximal sodium reabsorption (FPRNa), distal delivery, and fractional phosphate reabsorption were similar in all groups; a significant positive correlation was found between the fractional calcium reabsorption and the FPRNa, indicating that proximal tubular function was preserved and that the urinary calcium losses in RH and in the hypercalciuric PHPx patients (h-PHPx) occurred in the distal nephron. However, only h-PHPx patients had reduced renal plasma flow, renal blood flow, and GFR, as well as a high renal vascular resistance, which was even more evident after the calcium challenge. These findings lead us to conclude that RH and h-PHPx patients are very different, as far as kidney dysfunction is concerned, and that a hypercalcemic nephropathy is the most probable cause of the alterations in distal calcium reabsorption and renal hemodynamics found in the h-PHPx patients.

Increased biochemical markers of bone formation and resorption in primary hyperparathyroidism with special reference to patients with mild disease

OBJECTIVES

To evaluate the impact on bone turnover of primary hyperparathyroidism (pHPT) with special reference to patients with mild pHPT, using biochemical markers of bone formation and resorption.

DESIGN

A longitudinal study of patients with pHPT before and one year after surgical treatment.

SETTING

The Departments of Internal Medicine and Surgery, Lund University Hospital.

SUBJECTS

Forty consecutive patients with pHPT. Thirty of these patients had mild pHPT and are reported separately. Data on bone mineral was also compared to a reference population.

INTERVENTION

All patients were operated upon and restudied one year later.

MAIN OUTCOME MEASURES

Bone resorption and formation was studied by means of the serum concentrations of the telopeptide of the carboxyterminal region of type 1 collagen (ICTP) and of alkaline phosphatase (ALP), osteocalcin and the carboxyterminal propeptide of type 1 procollagen (PICP), respectively. Bone density was measured at the distal radius by single photon absorptiometry (SPA).

RESULTS

Bone formation markers consistently decreased after parathyroid surgery: ALP from 3.51 +/- 0.23 to 2.94 +/- 0.21 microkat L(-1) (P < 0.05), osteocalcin from 6.15 +/- 0.53 to 2.89 +/- 0.23 microg L(-1) (P < 0.001) and PICP from 126.4 +/- 10.9 to 96.0 +/- 6.5 microg L(-1) (P < 0.001). In parallel, the ICTP concentration, reflecting bone resorption, decreased from 5.10 +/- 0.54 to 3.94 +/- 0.34 microg L(-1) (P < 0.001). There was not any significant change in distal radius bone mineral 1 one year after surgery. In the subgroup of patients classified as mild pHPT, a significant decrease was noted for osteocalcin, PICP and for ICTP but not for ALP, without significant changes in variables reflecting distal radius bone mineral content. Glomerular filtration rate was inversely correlated to serum levels of intact PTH, ionized calcium, alkaline phosphatase, osteocalcin and ICTP and directly correlated to the 1.25-dihydroxy-vitamin D concentrations.

CONCLUSIONS

pHPT is associated with substantial changes in circulating levels of biochemical markers of bone formation and resorption. These findings are also present in patients with mild pHPT. Renal function should be considered in the evaluation of the impact of pHPT on bone turnover.