MSP430FR2111: Current drain is higher than expected while in LPM4

In my design the controller is in LPM4 in a base level loop while the ADC is configured to to do sampling in repeat single channel mode while looking for a voltage reading that exceeds a threshold. My ADC configuration is shown in the code excerpt below. During this loop, the measured current drain of the circuit is approximated 450uA. If this loop is executed with ADC sampling disabled, the current drain is approximately 110 uA. Therefore, it appears that having ADC sampling on is the root cause of the higher current. Is the higher current drain with ADC sampling enabled an expected consequence of doing the sampling, or is there a way to lower the current drain with the sampling enabled?

static const int fireThresholdFlu8_9 = 10;
//static const int fireThresholdFlu12 = 20;

// Configure ADC10 channel 4
ADCCTL0 &= ~ADCENC; // Disable ADC
ADCCTL0 |= ADCSHT_2 | ADCON | ADCMSC;        // ADCON, S&H=16 ADC clks; multiple conversions, those after 1st one done automatically
ADCCTL1 = ADCSHP_1 | ADCCONSEQ_2;             // ADCCLK = MODOSC; sample using timer; repeat single channel
ADCCTL2 = ADCRES_1;                                              // 10-bit conversion results
ADCIE = ADCHIIE;                                                          // Enable ADC above upper threshold interrupt

ADCHI = fireThresholdFlu8_9;

ADCMCTL0 = ADCINCH_4 | ADCSREF_0;               // A4 ADC external input select
ADCCTL0 |= ADCENC | ADCSC;                                 // Sampling and conversion start // Reference: V(R+)= 3V V(R-) = GND

channel = E_CHANNEL4;