Purpose: In primary hyperparathyroidism (PHPT), intraoperative localization of the parathyroid adenoma can be challenging, especially with negative pre-operative imaging. Some studies suggest a strong correlation between preoperative parathyroid hormone (PTH), calcium and phosphate with parathyroid adenoma size. We aim to review this hypothesis and determine their utility in intraoperative identification. Methodology: We retrospectively analysed data for all parathyroidectomies performed at single institution in last 5 years for primary PHPT. Results: Of 102 parathyroidectomies performed, 94 were performed for a single parathyroid adenoma, using minimally invasive approach in 76 (81%) patients. The mean age was 64 years with 71% being women. Parathyroid size and parathyroid weight indicated on the pathology report showed a strong positive linear correlation (ρ = 0.57, p < 0.001). Calcium had the strongest correlation with parathyroid size (ρ = 0.251, p < 0.02) and weight (ρ = 0.28, p < 0.02), whereas PTH and phosphate although demonstrated a correlation, were not statistically significant. Multivariable linear regression modelling with PTH, calcium, phosphate, and patient age significantly explained 18.4% of the variance in adenoma weight (R2 = 0.184, F(2, 55) = 6.221, p < 0.001) and 13.5% of variance in adenoma size (R2 = 0.13, F(1, 56) = 8.76, p < 0.001). Calcium was the only variable significantly associated with adenoma weight and size (p < 0.01). Conclusion: Our study did not demonstrate a strong association between preoperative PTH to predict parathyroid size and weight in PHPT. In cases of undetermined adenoma location, based on the multivariable regression model, adenoma size is difficult to estimate using these biochemical markers.