(ShareCast News) - Investec placed its 'hold' rating on Spire under review after the healthcare provider issued a profit warning.Investec said the first half results were worse than expected, with National Health Service revenue falling short of the 20% growth the brokerage had expected."We expected strong volumes as waiting lists were cleared ahead of the election, but these do not appear to have materialised," Investec said in a note to clients.While Spire downgraded its full year revenue and earnings guidance, Investec said its lowered earnings before interest, tax, depreciation and amortisation growth figure of between 4-6% was conservative.Investec said downgrades were expected, but Spire's valuation was supported by South African firm Mediclinic's investment in it. It was not yet clear if Mediclinic would buy out the rest of the hospital.In contrast, Berenberg retained a 'buy' rating, and said Friday's share price weakness offered a buying opportunity."We remain convinced that the long-term growth story for Spire is intact. Demand is robust and, if anything, pressure on the NHS is intensifying."The German bank said Spire was ultimately likely to benefit either through NHS outsourcing or through an increase in private work."Added to this, we believe the Mediclinic merger and acquisition potential is largely unaffected by today's events, given that we expect this weaker NHS demand to be short-term in nature," Berenberg said.At 1552 BST, Spire shares were down 13.2% at 348.60p.