OPKO Health (OPK -4.28%) is sizzling. Its shares skyrocketed 169% in 2020. The stock is up 32% so far this year.

However, OPKO's fourth-quarter and full-year results announcement after the market close on Thursday has jeopardized that impressive run. The healthcare stock slipped nearly 4% in after-hours trading following that update. Here are the highlights from OPKO's Q4 results.

Scientist looking through microscope.

Image source: Getty Images.

By the numbers

OPKO Health reported revenue of $494.6 million in the fourth quarter, a 121% year-over-year jump. This result easily topped the average analyst estimate of $443.1 million.

The company reported net income in the fourth quarter of $32.3 million, or $0.05 per share, based on generally accepted accounting principles (GAAP). OPKO delivered a GAAP net loss of $112.4 million, or $0.18 per share, in the prior-year period. The company's Q4 result narrowly beat the Wall Street consensus estimate of $0.04 per share.

OPKO ended the fourth quarter with cash, cash equivalents, and short-term investments of $72.2 million. The company also has access to an additional $57.6 million with its line of credit, plus another $100 million credit facility that could be tapped without any further dilution to its stock.

Behind the numbers

The big story for OPKO in the fourth quarter was its BioReference Laboratories diagnostics business. Revenue for this unit jumped 157% year over year to $457.9 million. Increased COVID-19 testing drove this tremendous growth. BioReference Labs' overall volume in Q4 soared 170% compared to 2019. Its COVID-19 polymerase chain reaction (PCR) testing volume increased 24% quarter over quarter.

There were some headwinds for OPKO's diagnostics business, though. The COVID-19 pandemic caused clinical test volume to drop off. Reimbursement for clinical and genomic tests was also lower in Q4.

OPKO's pharmaceuticals segment didn't perform so well in the fourth quarter. Revenue slipped nearly 4% year over year to $30.8 million. Sales for chronic kidney disease drug Rayaldee fell primarily because of the impact of the pandemic. Total prescriptions for the drug dropped from 17,900 in the prior-year period to 15,000 in Q4.

The company's total operating expenses increased 32% year over year. However, with revenue growing at a much faster rate, OPKO's bottom line improved significantly compared to the prior-year period.

Looking ahead

The U.S. Food and Drug Administration (FDA) should announce its approval decision for somatrogon in treating pediatric patients with growth hormone deficiency by October 2021. OPKO also plans to launch Rayaldee in several European countries later this year.

Arguably the main thing to watch with OPKO, though, is how COVID-19 testing volumes hold up as vaccines continue to roll out. It's possible that lower efficacy for the vaccines against new coronavirus variants could prolong the pandemic and boost demand for COVID-19 tests. However, OPKO could also see its COVID-19 testing revenue fall as the year progresses. Worries about this scenario appear to have outweighed the good news from the company's Q4 update.