Zinc levels in patients with lumbar disc herniation: A systematic review and meta-analysis

Introduction

Zinc is the most important trace element regarding matrix metalloproteinases (MMPs), which are the primary enzymes responsible for degeneration of the lumbar disc. Despite this, no connections have been made between zinc levels and lumbar disc herniation (LDH).

Methods

A systematic search of Scopus, Web of Science, PubMed, Embase, and Cochrane Library databases was performed to identify studies that measure the levels of serum or intervertebral disc (IVD) zinc levels in LDH patients. Three meta-analyses were preformed: A single-arm meta-analysis was done for each of the serum and IVD zinc levels and a double-arm meta-analysis that compared serum zinc levels between LDH and healthy controls.

Results

A total of 11 studies were included: six evaluated serum zinc levels, and five assessed IVD zinc concentrations. Compared with healthy controls, serum zinc levels were significantly lower in patients with LDH (SMD = –1.02; 95 % CI: –1.91 to –0.12; P < 0.0001). The pooled mean serum zinc concentration, from four studies, was 98.7 μg/dL (95 % CI: 79.8–117.7; P < 0.001). In addition, four studies reporting IVD zinc concentrations yielded a pooled mean of 30.27 mg/kg (95 % CI: 18.1–42.4; P < 0.001).

Conclusion

This review revealed that patients with LDH tend to have lower serum zinc concentrations compared to healthy controls. In certain studies, zinc levels within IVD appear to be more elevated than controls. These findings can be interpreted as a hypothesis about zinc allocation where zinc is redistributed from the bloodstream to degenerated disc tissue, possibly driven by increased demands from the upregulated MMP levels rather than reflecting a primary systemic deficiency. Future studies are needed to validate this relationship.