* Net investment income falls by 90 pct
* Impairment charges rise at HighMount Exploration
* Revenue flat at $3.73 bln
April 29 (Reuters) - Hotel, energy and financial services conglomerate Loews Corp reported a 34 percent drop in first-quarter profit due to higher impairment charges and a sharp fall in investment income.
Net income at the company controlled by the billionaire Tisch family fell to $242 million, or 62 cents per share, from $367 million, or 92 cents per share, a year earlier.
The fall was mainly due to a sharp decline in the net investment income for the quarter to $5 million from $50 million a year earlier.
During the quarter, Loews also took an impairment charge of $92 million at its HighMount Exploration & Production unit related to the value of its natural gas and oil properties.
A year earlier, HighMount had impairment charges of $28 million.
Loews, which has interests ranging from insurance and luxury hotels to energy exploration and natural gas pipelines, said revenue remained largely flat at $3.73 billion.
Separately, Loews' largest holding, CNA Financial Corp , said operating income rose marginally to $231 million, or 86 cents per share, from $226 million, or 84 cents per share, a year earlier.
Analysts had expected CNA Financial to earn 71 cents per share, according to Thomson Reuters I/B/E/S.
Another unit, Diamond Offshore Drilling, which accounts for about a quarter of Loews's revenues, reported first-quarter results above analysts' expectations last week, helped by higher utilization of its deepwater units.
Loews's shares closed at $44.44 on the New York Stock Exchange on Friday.