Concentration of Serum Calcium Is Not Correlated with Symptoms Or Severity of Primary Hyperparathyroidism: an Examination of 20,081 Consecutive Adults
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Concentration of serum calcium is not correlated with symptoms or severity of primary hyperparathyroidism: An examination of 20,081 consecutive adults Deva Boone, MD, Douglas Politz, MD, Jose Lopez, MD, Jamie Mitchell, MD, Kevin Parrack, MD, and James Norman, MD, Tampa, FL Background. Guidelines for operative treatment of primary hyperparathyroidism include calcium levels >1 mg/dL above normal. We sought to determine whether greater calcium concentrations were associated with increased symptoms or disease severity. Methods. A retrospective review of a prospectively maintained database of adults undergoing parathyroidectomy for primary hyperparathyroidism, grouped according to greatest preoperative calcium level: those patients with calcium concentrations between 10.0 and 11.0 mg/dL and those with >11.0 mg/dL. We compared subjective symptoms and objective measures of disease severity. Results. The review included 20,081 adults who were split nearly evenly between calcium concentrations between 10.0 and 11.0 (10,430, 51.9%) and those with >11.0 mg/dL (9,651, 48.1%). In both groups, an absence of symptoms related to primary hyperparathyroidism was uncommon (<5%). All subjective and objective measures of disease severity were nearly identical with no significant differences (percentages for calcium concentrations between 10.0 and 11.0 and those with >11.0 mg/dL, respectively), including fatigue (72% for both groups), heartburn (37% vs 34%), bone pain (50% vs 48%), sleep disturbances (68% vs 65%), osteoporosis (40% in both groups), kidney stones (21% vs 22%), chronic kidney disease with glomerular filtration rate <60 (29% vs 32%), and hypertension (50% vs 53%). Conclusion. Serum calcium concentrations of greater than or less than 11 mg/dL are unrelated to symptoms and disease severity in primary hyperparathyroidism. There is no evidence to support a serum calcium threshold in parathyroidectomy guidelines. (Surgery 2017;161:98-106.) From the Norman Parathyroid Center, Tampa, FL THERE IS UNIVERSAL AGREEMENT that symptomatic pri- asymptomatic or mildly symptomatic pHPT allows mary hyperparathyroidism (pHPT) should be great latitude in its management, with some arguing treated by parathyroidectomy (PTX). In contrast, for a proactive approach1 while others advocate for operative referral only when some triggering event has occurred, such as the development of kidney The authors report no outside sources of financial support. stones or a worsening biochemical profile.2 Societal paper for the American Association of Endocrine If long-term monitoring is the chosen route, it Surgery. Abstract presented at the American Association of has been taught that the development of greater Endocrine Surgery 37th annual meeting, April 12, 2016, Baltimore, MD. serum calcium levels also would trigger operative Accepted for publication September 22, 2016. referral. The assumption has been that greater Reprint requests: Deva Boone, MD, Norman Parathyroid Cen- calcium levels are associated with greater rates of ter, 2400 Cypress Glen Drive, Wesley Chapel, FL 33544. complications, signs, and symptoms. The recom- E-mail: [email protected]. mendations of the 1990 National Institutes of 0039-6060/$ - see front matter Health (NIH) Consensus Conference on the Ó 2016 Elsevier Inc. All rights reserved. treatment of asymptomatic pHPT stated that “con- http://dx.doi.org/10.1016/j.surg.2016.09.012 scientious surveillance may be justified in patients 98 SURGERY Surgery Boone et al 99 Volume 161, Number 1 whose calcium levels are only mildly elevated and “mild” hypercalcemia (#11 mg/dL) to those with whose renal and bone status are close to normal.”3 greater levels (>11 mg/dL). Unfortunately, symptomatic disease was defined rather narrowly.4 Conditions defining symptom- atic disease included kidney stones, substantial METHODS loss of bone density, chronic kidney disease, clini- We performed a retrospective review of a single- cally relevant neuromuscular derangements, and institution, prospective database of patients who gastrointestinal manifestations. The more com- were operated on for pHPT during 13 consecutive mon, nonspecific symptoms of fatigue, general years ending in January 2016. All patients signed malaise, and body aches, which could be attrib- consent for review of their clinical data which were uted to other common ailments, were excluded. collected in a nonidentifiable fashion. This study If a stricter definition of symptoms is adhered was approved by our Institutional Review Board. to, most patients with pHPT will be considered For this review, we included only adults $21 years asymptomatic.5,6 old with pHPT; patients with secondary and These guidelines have since been updated 3 tertiary HPT were excluded. In addition, patients times at the International Workshops on the Man- with greatest serum calcium levels <10.0 mg/dL agement of Asymptomatic PHPT,7,8 most recently (ie, those with normocalcemic pHPT) were in 2014,2 with refinements to their recommenda- excluded from this analysis for 2 reasons. First, tions for following “asymptomatic” patients who these patients are usually diagnosed only after they are monitored long term to evaluate for kidney have developed severe, end-organ disease (eg, and bone disease. Using the assumption that osteoporotic fracture) because most physicians greater serum calcium concentrations indicate do not check parathyroid hormone (PTH) levels greater disease severity, the guidelines always have in the setting of normal calcium levels. Second, recommended PTX when the calcium reached a our experience with normocalcemic pHPT has led certain threshold. For the past several decades, us to use stricter criteria for operating on patients this trigger for operative referral was a serum cal- with calcium levels <10.0 mg/dL; we usually cium level >1.0 mg/dL above normal, with normal require these patients to have objective evidence defined by the reporting laboratory.2 of end-organ damage or symptoms that cannot be Although we now have evidence from high-quality attributed to other causes. Our approach to these studies on the deleterious effects of untreated patients would necessarily skew any comparisons pHPT,6,9 there are no studies to show that greater on symptoms, and thus we excluded this group. In serum calcium concentrations lead to or equate all, 20,081 consecutive adults undergoing PTX for with greater disease severity.10 The relationship be- classic hypercalcemic pHPT were studied. tween serum calcium concentrations and pHPT Collection of patient data. In our practice, all severity is established only in cases of hypercalcemic patients complete a preoperative questionnaire crisis, a very uncommon presentation of pHPT.11 specific to HPT, which is combined with laboratory Many authors seem to make the assumption that values, test results, comorbidities, and operative the degree of increase in serum calcium concentra- findings to establish a robust database that in- tion is an approximation of disease duration, a hy- cludes up to 70 parameters per patient. In addition pothesis that never has been confirmed and has to the standard questions addressing medical, even been refuted in some long-term studies.12 operative, and medication history, our intake Despite a lack of evidence, the supposition that questionnaire includes detailed questions on the “mild hypercalcemia” equates to mild hyperpara- common symptoms of HPT, known causes of thyroidism is common in the literature and in pHPT such as lithium use, family medical history, clinical practice. But in treating many patients with and known end-organ manifestations of HPT, pHPT annually, we have noticed that those with including cardiac arrhythmias, chronic kidney dis- classic pHPT symptoms often have rather unim- ease or stones, hypertension, gastroesophageal pressive biochemical profiles. It has long been our reflux disease, and bone loss (Appendix A, online hypothesis that the degree of increase in serum version only). Patient medical records are ob- calcium concentration does not predict disease tained, with a focus on obtaining all recorded cal- severity; that a patient with a greater serum cal- cium, ionized calcium, and PTH levels, results of cium concentration is not necessarily “sicker” than any recent bone density/dual-energy X-ray absorp- one with mild hypercalcemia. In this study, we tiometry (DEXA) scan results, creatinine and sought to test this hypothesis by comparing the glomerular filtration rate (GFR) results, imaging symptoms and end-organ effects in patients with or physician documentation of kidney stones, as 100 Boone et al Surgery January 2017 Table. Demographic and biochemical data for patients with greatest serum calcium levels between 10.0–11.0 mg/dL (Ca #11) and those with their greatest calcium levels >11.0 mg/dL (Ca >11) Calcium Calcium 10–11 >11 P value No. 10,430 9,651 Age (y)* 61.4 ± 11.6 60.8 ± 12.7 .4 Female (n, %) 8,328, 80% 7,137, 74% <.001 Male (n, %) 2,102, 20% 2,514, 26% Greatest serum 102 ± 57 130 ± 99 <.001 PTH (pg/mL)* Median PTH 92 107 (pg/mL) Mode PTH 76 78 (pg/mL) Ionized calcium 5.6 ± 0.4 6.1 ± 0.5 <.001 Fig 1. Distribution of patients with primary hyperpara- (mg/dL)* thyroidism, according to their greatest preoperative Vitamin D 26 ± 16 23 ± 13 .2 serum calcium levels. Patients with calcium levels be- (ng/mL)* tween 10.0 and 11.0 mg/dL comprised 51.9% of the Urine calcium 270 ± 160 310 ± 213 <.001 study population, while 48.1% had calcium levels of (mg/24 h)* $11.1. Mean calcium = 11.1 ± 1.2 mg/dL; mode = 11.0; median = 11.0. All values above 14.0 mg/ *Mean ± standard deviation. dL are shown with that group. 80% vs 74% respectively (P < .001). Preoperative well as physician records to confirm other end- vitamin D-25-OH levels were available for 9,674 pa- organ effects of HPT. tients, with vitamin D level being similar for both Statistical analysis. Patients were grouped by the groups: 26 ± 16 ng/mL for Ca #11 vs greatest recorded preoperative serum calcium con- 24 ± 13 ng/mL for Ca >11 (P = .2).