Oliguria or hypouresis (both names from roots meaning not enough urine) is the low output of urine. In humans, it is clinically classified as an output more than 80 ml/day but less than 400ml/day.
The alternative is to take US Dollars with you, and then change your money in Colombia, but if you do want to take cash then it's probably easiest to just buy Colombian pesos in the UK and take them. The alternative is to rely on using your bank card to withdraw money in Colombia. There is a decent network of cash machines in Colombia and they take most UK bank cards so there shouldn't be a problem with this, but many people do prefer to take a pre-paid currency card instead.
The Balboa. Technically the official currency is the Balboa, however, in 1941 Panama stopped printing the Balboa in favor of using the american dollar. Panama does still mint coins in the denominations of 1, 5, 10, 25, 50 and 100 which are the same metal, size and shape of the equivalent american coins.