Medical group EKF Diagnostics warned on annual profits after taking a currency hit and saying revenue from newly acquired companies was likely to be lower than expected.EKF said acquisitions during the year of Diaspect, Selah Genomics and STI were set to contribute at least £6.1m to overall revenue and to collectively boost group earnings.That was lower than anticipated for Diaspect and Selah, but EKF added: "We're confident that traction gained in the fourth quarter of 2014 has established a solid foundation for future revenue growth in the coming year."The company expects unaudited revenues for the year to 31 December will show at least a 24% rise on the previous year to £39.5m.The second half is expected to show a substantial improvement on the growth seen in the first half, despite the continued negative impact of exchange rates estimated at about £1.9m over the year.Unaudited adjusted pre-tax earnings before interest, depreciation and amortisation (EBITDA) was expected to be at least 29% up on the previous year at £6.2m.Excluding the effect of exchange rates, revenue would have been expected to be up at least 30% year-on-year and adjusted EBITDA would have been at least 37% higher, EKF said.It added: "The company remains confident of strong growth in 2015, both from the continued strong organic growth, but also through a full-year contribution from the three recent acquisitions."Shares fell 4.1p or 15.2% to 23p at 09:33 in London.