“The relationship between mild primary hyperparathyroidism (pHPT) and cardiovascular (CV) disease has not been fully understood,” explains Stella Bernardi, MD, PhD. “Previous research has shown that patients with pHPT exhibit vascular and myocardial calcifications, hypertension, and left ventricular hypertrophy, which account for the risk of CV mortality. This seems to be a feature specific to severe pHPT, however, and current literature on the effects of mild pHPT and parathyroidectomy (PTX) on CV disease provides unclear results.”

For a paper published in The Journal of Clinical Endocrinology & Metabolism, Dr. Bernardi and colleagues investigated whether mild pHPT increases arterial stiffness, a predictor of CV morbidity and mortality, and if PTX could reduce it. They conducted a systematic review of the literature and performed a meta-analysis. “We screened studies that evaluated the effects of mild pHPT and PTX upon arterial stiffness, and among them, we selected those in which arterial stiffness was assessed by pulse wave velocity (PWV), the gold standard of measurement,” she says. “To our knowledge, this is the first meta-analysis to assess PWV in patients with mild pHPT compared with controls, as well as before and after PTX,” Dr. Bernardi says.

PTX Could Reduce of CV Disease in Patients With Mild pHPT

Nine observational studies and one randomized controlled trial were selected, including 433 patients with mild pHPT, 171 of whom underwent PTX, and 407 controls.  PWV was significantly higher in mild in those with pHPT when compared with controls (mean difference [MD], 1.18; 0.67 to 1.68). Seven studies evaluated the effect of PTX on PWV and showed collectively that PTX significantly reduced PWV (MD, -0.48; -0.88 to -0.07).

The study team found that patients with mild pHPT had significantly higher pulse wave values (ie, higher arterial stiffness) than controls. “This indicates that mild pHPT does have an effect on the vessels and the CV risk profile of patients with mild pHPT,” she says (Figure 1). “We also found that PTX significantly reduced arterial stiffness in patients with mild pHPT, which suggests that PTX could reduce the risk of CV disease in patients with mild pHPT (Figure 2).” 

CV Involvement in Patients Should Not Be Dismissed

Dr. Bernardi notes that CV involvement in patients with mild pHPT should not be dismissed. “Physicians, particularly endocrinologists, should look for signs of CV involvement in patients with mild pHPT, such as arterial stiffness,” she says.

The limitations of this meta-analysis include most of the studies being small and non-randomized, with only a few evaluating the effects of PTX on PWV, according to Dr. Bernardi and colleagues. They express the need for studies with larger cohorts to address this and confirm their findings. “Future research focusing on this area of study should seek to clarify how to assess the CV risk profile of patients with mild pHPT, identify PWV thresholds, and indicate if there are subgroups of patients who might benefit most from PTX,” Dr. Bernardi adds.